Vertex shader with primitive replication

ABSTRACT

An embodiment of a semiconductor package apparatus may include technology to determine one or more conditions for a set of primitives, and perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives. Other embodiments are disclosed and claimed.

TECHNICAL FIELD

Embodiments generally relate to graphics systems. More particularly, embodiments relate to a vertex shader with primitive replication.

BACKGROUND

United States Patent Publication No. 20160086299 describes a position-only shading pipeline. In position-only shading, two geometry pipes exist, a trimmed down version called the cull pipe and a full version called the replay pipe. Thus, the cull pipe executes the position shaders in parallel with the main application, but typically generates the critical results much faster as it fetches and shades only the position attribute of the vertices and avoids the rasterization as well as the rendering of pixels for the frame buffer. Furthermore, the cull pipe uses these critical results to compute visibility information for all the triangles whether they are culled or not. On the other hand, the replay pipe consumes the visibility information to skip the culled triangles and shades only the visible triangles that are finally passed to the rasterization phase. Together the two pipes can hide the long cull runs of discarded triangles and can complete the work faster in some embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The various advantages of the embodiments will become apparent to one skilled in the art by reading the following specification and appended claims, and by referencing the following drawings, in which:

FIG. 1 is a block diagram of an example of graphics processing system according to an embodiment;

FIG. 2 is a block diagram of an example of a semiconductor package apparatus according to an embodiment;

FIGS. 3A to 3C are flowcharts of an example of a method of processing graphics according to an embodiment;

FIG. 4 is a block diagram of an example of an electronic processing system according to an embodiment;

FIG. 5 is a block diagram of an example of a graphics pipeline according to an embodiment;

FIG. 6 is a block diagram of an example of a graphics processing system according to an embodiment;

FIG. 7 is a block diagram of an example of a graphics processor unit (GPU) architecture according to an embodiment;

FIG. 8 is a block diagram of another example of a graphics processor unit (GPU) architecture according to an embodiment;

FIG. 9 is a block diagram of another example of a graphics processor unit (GPU) architecture according to an embodiment;

FIG. 10 is a block diagram of an example of a processing system according to an embodiment;

FIG. 11 is a block diagram of an example of a processor according to an embodiment;

FIG. 12 is a block diagram of an example of a graphics processor according to an embodiment;

FIG. 13 is a block diagram of an example of a graphics processing engine of a graphics processor according to an embodiment;

FIG. 14 is a block diagram of an example of hardware logic of a graphics processor core according to an embodiment;

FIGS. 15A to 15B illustrate an example of thread execution logic according to an embodiment;

FIG. 16 is a block diagram illustrating an example of a graphics processor instruction formats according to an embodiment;

FIG. 17 is a block diagram of another example of a graphics processor according to an embodiment;

FIG. 18A is a block diagram illustrating an example of a graphics processor command format according to an embodiment;

FIG. 18B is a block diagram illustrating an example of a graphics processor command sequence according to an embodiment;

FIG. 19 illustrates an example graphics software architecture for a data processing system according to an embodiment;

FIG. 20A is a block diagram illustrating an example of an IP core development system according to an embodiment;

FIG. 20B illustrates an example of a cross-section side view of an integrated circuit package assembly according to an embodiment;

FIG. 21 is a block diagram illustrating an example of a system on a chip integrated circuit according to an embodiment;

FIGS. 22A to 22B are block diagrams illustrating exemplary graphics processors for use within an SoC, according to embodiments; and

FIGS. 23A to 23B illustrate additional exemplary graphics processor logic according to embodiments.

DESCRIPTION OF EMBODIMENTS

Turning now to FIG. 1, an embodiment of a graphics processor system 10 may include a processor 11, memory 12 communicatively coupled to the processor 11, and logic 13 communicatively coupled to the processor 11 and memory 12 to determine one or more conditions for a set of primitives, and perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives. In some embodiments, the logic 13 may be configured to reconfigure a graphics pipeline to perform primitive replication at the vertex shader. For example, the logic 13 may be configured to configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives. For example, each of the first and second targets respectively may include one or more of a render target and a viewport. In some embodiments, the logic 13 may be further configured to determine a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, determine a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and determine a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport. For example, the logic 13 may be also be configured to determine if each of the first, second, and third conditions are met, and if met, to move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and move operations related to all other output attributes from the geometry shader to the vertex shader. In some embodiments, the logic 13 may be located in, or co-located with, various components, including the processor 11 (e.g., on a same die).

A primitive, for example, may correspond to a basic graphics construct. In some embodiments, a primitive may correspond to a collection of vertices which define a polygon or other shape. For example, a primitive may correspond to a triangle. In some embodiments herein, the first viewport may correspond to a left eye viewport of a stereo virtual reality system and the second viewport may correspond to a right eye viewport of the stereo virtual reality system. Alternatively, for example, the first viewport may be part of a first set of viewports which correspond to a first face of a cube rendering system and wherein the second viewport may be part of a second set of viewports which corresponds to a second face of the cube rendering system. For example, there may be six viewports corresponding to each face of the cube. In another alternative example, the first viewport may correspond to a first cascade of a cascaded shadow map and the second viewport may correspond to a second cascade of the cascaded shadow map (e.g. for two or more viewports, only limited by the number of viewports). As noted above, while some embodiments are described in connection with replicating primitives to a first and second viewport, in practice some embodiments may perform such replication to more than two viewports. Those skilled in the art will appreciate that there are many other applications which may benefit from multiple render targets and/or multiple viewports.

Embodiments of each of the above processor 11, memory 12, logic 13, and other system components may be implemented in hardware, software, or any suitable combination thereof. For example, hardware implementations may include configurable logic such as, for example, programmable logic arrays (PLAs), field programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), or fixed-functionality logic hardware using circuit technology such as, for example, application specific integrated circuit (ASIC), complementary metal oxide semiconductor (CMOS) or transistor-transistor logic (TTL) technology, or any combination thereof. Embodiments of the processor 11 may include a general purpose processor, a special purpose processor, a central processor unit (CPU), a graphics processor unit (GPU), a kernel, an execution unit, a controller, a micro-controller, etc.

Alternatively, or additionally, all or portions of these components may be implemented in one or more modules as a set of logic instructions stored in a machine- or computer-readable storage medium such as random access memory (RAM), read only memory (ROM), programmable ROM (PROM), firmware, flash memory, etc., to be executed by a processor or computing device. For example, computer program code to carry out the operations of the components may be written in any combination of one or more operating system (OS) applicable/appropriate programming languages, including an object-oriented programming language such as PYTHON, PERL, JAVA, SMALLTALK, C++, C# or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. For example, the memory 12, persistent storage media, or other system memory may store a set of instructions which when executed by the processor 11 cause the system 10 to implement one or more components, features, or aspects of the system 10 (e.g., the logic 13, determining the one or more conditions for the set of primitives, performing primitive replication at the vertex shader, etc.).

Turning now to FIG. 2, an embodiment of a semiconductor package apparatus 20 may include one or more substrates 21, and logic 22 coupled to the one or more substrates 21, wherein the logic 22 is at least partly implemented in one or more of configurable logic and fixed-functionality hardware logic. The logic 22 coupled to the one or more substrates 21 may be configured to determine one or more conditions for a set of primitives, and perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives. In some embodiments, the logic 22 may be configured to reconfigure a graphics pipeline to perform primitive replication at the vertex shader. For example, the logic 22 may be configured to configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives. For example, each of the first and second targets respectively may include one or more of a render target and a viewport. In some embodiments, the logic 22 may be further configured to determine a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, determine a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and determine a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport. For example, the logic 22 may be also be configured to determine if each of the first, second, and third conditions are met, and if met, to move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and move operations related to all other output attributes from the geometry shader to the vertex shader. In some embodiments, the logic 22 coupled to the one or more substrates 21 may include transistor channel regions that are positioned within the one or more substrates 21.

Embodiments of logic 22, and other components of the apparatus 20, may be implemented in hardware, software, or any combination thereof including at least a partial implementation in hardware. For example, hardware implementations may include configurable logic such as, for example, PLAs, FPGAs, CPLDs, or fixed-functionality logic hardware using circuit technology such as, for example, ASIC, CMOS, or TTL technology, or any combination thereof. Additionally, portions of these components may be implemented in one or more modules as a set of logic instructions stored in a machine- or computer-readable storage medium such as RAM, ROM, PROM, firmware, flash memory, etc., to be executed by a processor or computing device. For example, computer program code to carry out the operations of the components may be written in any combination of one or more OS applicable/appropriate programming languages, including an object-oriented programming language such as PYTHON, PERL, JAVA, SMALLTALK, C++, C# or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages.

The apparatus 20 may implement one or more aspects of the method 25 (FIGS. 3A to 3C), or any of the embodiments discussed herein. In some embodiments, the illustrated apparatus 20 may include the one or more substrates 21 (e.g., silicon, sapphire, gallium arsenide) and the logic 22 (e.g., transistor array and other integrated circuit/IC components) coupled to the substrate(s) 21. The logic 22 may be implemented at least partly in configurable logic or fixed-functionality logic hardware. In one example, the logic 22 may include transistor channel regions that are positioned (e.g., embedded) within the substrate(s) 21. Thus, the interface between the logic 22 and the substrate(s) 21 may not be an abrupt junction. The logic 22 may also be considered to include an epitaxial layer that is grown on an initial wafer of the substrate(s) 21.

Turning now to FIGS. 3A to 3C, an embodiment of a method 25 of processing graphics may include determining one or more conditions for a set of primitives at block 28, and performing primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives at block 29. Some embodiments of the method 25 may include reconfiguring a graphics pipeline to perform primitive replication at the vertex shader at block 30. For example, the method 25 may include configuring the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives at block 31. For example, each of the first and second targets may respectively include one or more of a render target and a viewport at block 32. Some embodiments of the method 25 may further include determining a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader at block 33, determining a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold at block 34, and determining a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport at block 35. For example, the method 25 may also include determining if each of the first, second, and third conditions are met at block 36, and if met, moving operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader at block 37, and moving operations related to all other output attributes from the geometry shader to the vertex shader at block 38.

Embodiments of the method 25 may be implemented in a system, apparatus, computer, device, etc., for example, such as those described herein. More particularly, hardware implementations of the method 25 may include configurable logic such as, for example, PLAs, FPGAs, CPLDs, or in fixed-functionality logic hardware using circuit technology such as, for example, ASIC, CMOS, or TTL technology, or any combination thereof. Alternatively, or additionally, the method 25 may be implemented in one or more modules as a set of logic instructions stored in a machine- or computer-readable storage medium such as RAM, ROM, PROM, firmware, flash memory, etc., to be executed by a processor or computing device. For example, computer program code to carry out the operations of the components may be written in any combination of one or more OS applicable/appropriate programming languages, including an object-oriented programming language such as PYTHON, PERL, JAVA, SMALLTALK, C++, C# or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages.

For example, the method 25 may be implemented on a computer readable medium as described in connection with Examples 20 to 25 below. Embodiments or portions of the method 25 may be implemented in firmware, applications (e.g., through an application programming interface (API)), or driver software running on an operating system (OS). Additionally, logic instructions might include assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, state-setting data, configuration data for integrated circuitry, state information that personalizes electronic circuitry and/or other structural components that are native to hardware (e.g., host processor, central processing unit/CPU, microcontroller, etc.).

Some embodiments may advantageously transfer the geometry replication from the geometry shader to the vertex shader with a primitive replication hardware (HW) feature. Some embodiments may reduce the computation overhead related to per-eye (e.g., per viewport) geometry replication in some virtual reality (VR) applications. Some other graphics system may handle geometry replication in the VR applications with replicated draw calls at a DirectX/OpenGL API level, geometry replication at the geometry shader level, or explicit usage of API extensions allowing multiplication of geometry per render targets (e.g., which may be referred to as multiview extensions). With respect to replicated draw calls at the API level, such an approach incurs performance overhead in application and graphics driver (e.g., 2 times (2×) or more draw calls). Geometry replication at the geometry shader level may incur low GPU performance. In general, the geometry shader may provide geometry expansion possibilities. However, in the case of VR applications where commonly only the one vertex's attribute is replicated (e.g., position) the usage of the geometry may be inaccurate and may not boost GPU performance as expected. With respect to multiview extensions, this approach may enforce on application developers a separate implementation dedicated to primitive replication extension compliant HW only.

In contrast to conventional approaches, some embodiments may transfer the geometry replication from the geometry shader to the vertex shader while making use of a primitive replication HW feature whenever it is possible. For example, a graphics driver may detect the particular scenarios in the users' applications where the transfer may be applied and adjust the graphics pipeline to move geometry replication to the vertex shader stage. Advantageously, some embodiments may reduce the number of the shaders instances that must be dispatched and executed as well as an amount of data moved to perform a geometry replication. Some embodiments may also have a positive impact on overcoming the CPU and/or GPU overhead by reducing the time required to perform geometry replication in a three-dimensional (3D) geometry pipeline. Also, applications that do not use API extensions may get a similar performance gain as if they used the extension (e.g., some embodiments may not require HW/driver systems to be multiview extension compliant).

Turning now to FIG. 4, an embodiment of an electronic processing system 40 may include a central processor unit (CPU) portion (e.g. above the dashed line) and a GPU portion (e.g. below the dashed line). The CPU portion may support graphics applications 41 (e.g. 3D applications) and graphics (gfx) drivers 42 (e.g. 3D gfx drivers), while the GPU portion may support an enhanced vertex shader (VS) 43 (e.g., including hull shaders (HS), domain shaders (DS), geometry shader (GS) logic, logic related to position calculation, etc.), a raster stage 44, and a pixel shader (PS)/output merger stage 45. In some graphics and/or 3D applications, the same geometry may be projected into different viewports and/or render target array slices, with only the position attribute substantially varying between the different viewports/slices. Some usage scenarios include, but are not limited to virtual reality (VR), cubemap rendering and voxel lighting, and cascaded shadow maps. At the CPU portion, a conventional graphics application may use multi-pass rendering and/or replicate draw-calls at the DirectX/OpenGL application programming interface (API) level for the various viewports/slices. Multi-pass rendering or multiple draw calls, however, may incur a performance overhead in the CPU portion (e.g. the graphics application 41 and/or graphics driver 42). At the GPU portion, some other system may have replication occur at a GS (e.g., positioned between a conventional VS and the raster stage 44). Replication at the GS, however, may also hinder GPU performance optimizations by separating similar geometry objects so there is little cache reuse. GPUs may also incur heavy performance overhead in enabling the geometry shaders in the GPUs and not all APIs support the geometry shaders.

Advantageously, some embodiments of the electronic processing system 40 may perform primitive replication at the vertex shader 43. For example, new API constructs may enable primitive replication at the vertex shader 43, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver 42 may include primitive replication commands and the vertex shader 43 may include logic related to position calculation (e.g., moved from the GS to the VS).

In accordance with some embodiments, a method and/or apparatus may enable the primitives to be replicated across multiple viewports with per viewport changes in the position attribute. Advantageously, replicating primitives for multiple viewports with per viewport changes in the position attribute may enable graphics software to perform operations such as stereo rendering, cube map rendering, and/or cascaded shadow map generation in a single pass thus saving on repeating, for example, vertex shading and tessellation. Some embodiments may also provide an implementation for effective primitive replication per viewport in a position only shader based GPU architecture and GPUs using tile based rendering.

In some embodiments, the GPU portion may include a primitive replication HW feature (e.g., as discussed in more detail below) which allows the vertex shader 43 to replicate the system interpreted position output vertex attribute. Those replicas may be assigned to multiple render targets and/or viewports.

Some embodiments may transfer geometry replication from the geometry shader to the vertex shader if and only if the following conditions are met: 1) in the GS, only the layer and/or viewport together with position output attributes are changed per emitted vertex; 2) the number of declared emitted vertices in the GS is small enough to meet the primitive replication feature limitations; and 3) each vertex from the GS is emitted into either separate render target or separate viewport. To perform the replication at the VS stage instead of the GS stage, some embodiments of a graphics driver may take the following steps: 1) the compiler unit may detect if the geometry shader meets the aforementioned conditions; 2) the logic related to position, layer and/or viewport calculations may then be moved from the GS to the VS (e.g., dedicated technology to perform position replication at the VS stage may applied, using a HW primitive replication feature); 3) the remaining logic related to the rest of the output attribute (e.g., constant per emitted vertex) calculations may be moved from the GS to the VS as regular outputs computation; 4) the compiler unit may notify the graphics driver state unit to apply the 3D primitive replication geometry commands instead of regular commands; and 5) the graphics driver state unit does not submit the geometry shader commands to the HW. Advantageously, some embodiments may provide power and performance gains because the GS is not executed, and the outputs attributes that were emitted-vertex-invariant are only sent once instead of being sent multiple times (e.g., per emitted vertex) across all emitted vertices in the GS.

Turning now to FIG. 5, an embodiment of a graphics pipeline 50 shows one example of a primitive replication capability in a graphics pipeline. Without being limited to specific implementations, some useful example data structures may be provided in accordance with various embodiments. A state packet according to an embodiment may be defined that may be exposed to an API as an additional 3D state structure referred to as 3DSTATE_PRIMITIVE_REPLICATION. This state structure may be input, for example, by the vertex shader 43 and the information provided may be used in the primitive replication process. Pseudo-code for the data structure may be represented as follows:

typedef struct 3DSTATE_PRIMITIVE_REPLICATION { INT numReplicas; INT replicaMask; INT[16] VPAIoffsets; INT[16] RTAIoffsets; } where: numReplicas specifies the number of replica positions produced by the last pre-raster shader (e.g., this value matches the position array length of the last pre-raster shader); replicaMask specifies which replicas should be drawn (e.g., if bit k (0<=k<16) is clear, then replica k will not be rasterized; bits k>=numReplicas may be ignored); RTAIOffsets specifies an offset to add to SV_RenderTargetArrayIndex for each replica (e.g. where SV may indicate a system generated value); and VPAIOffsets specifies an offset to add to SV_ViewportArrayIndex for each replica.

In some embodiments, a data structure referred to as “POS” and a vertex header data structure referred to as “VERTEX HEADER” may also be defined that contains an array of position attributes along with other data associate with vertex data (e.g. where VPI corresponds to a viewport index). This data structure may be populated by the last active shader stage before the rasterizer. Pseudo-code for the data structure may be represented as follows:

typedef struct POS { FLOAT X; FLOAT Y; FLOAT Z; FLOAT W; } typedef struct VERTEX_HEADER { INT32 RTAI; INT32 VPI; INT32 PointWidth; POS[numReplica] POSITION; }

The graphics pipeline 50 may utilize the above-described data structure(s) at a last active vertex shader stage 51. The last active vertex shader stage 51 before the primitive assembly may write multiple positions (e.g. Vtx_Pos[0] through Vtx_Pos[N] for N+1 viewports) into the vertex 52 along with the header if primitive replication is enabled by the state. A first clipper 53 a may generate the right vertex data addresses for accessing the multiple positions but may use the same address for the attribute data. A primitive replication block 53 b may input these vertices, create the object, and replicate the primitives as per the state parameters by appropriately offsetting the viewport and render target indices. All the new positions may go through the perspective divide and normalized device coordinates (NDC) stage 53 c and clip test logic 54 for the multiple viewports 55. The remainder of the functions 56 may happen normally on the replicated primitives.

The graphics pipeline 50 may advantageously provide primitive replication support in the raster pipeline. The raster pipeline may build the primitive for position related data and the replicated primitive offset positions. Each replicated object may have support for its own viewport and render target, advantageously giving more flexibility. Packing the position data for the replications adjacently may provide a caching benefit and may reduce the position read bandwidth. After the replication of the primitive, the rest of the graphics pipeline may need minimal changes. Advantageously, some embodiments of the graphics pipeline 50 may perform primitive replication at the vertex shader 51. For example, new API constructs may enable primitive replication at the vertex shader 51, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments a graphics driver may include primitive replication commands and the vertex shader 51 may include logic related to position calculation (e.g., moved from the GS to the VS).

Turning now to FIG. 6, an embodiment of a graphics processing system 60 may include a replay pipe 61 and a cull pipe 62. Some embodiments may provide primitive replication in the cull pipe instead of, or in addition, to providing primitive replication in the replay pipe. For example, the system 60 may include primitive replication 63 in the cull pipe 62, and the object visibility recording 64 may pass the culled/render information to the replay pipe 61.

Turning now to FIGS. 7 and 8, an embodiment of a GPU architecture 70 may follow a virtual geometry pipeline 71 in which the vertices are transformed via vertex shaders 71 b-e, then the pixels are rasterized from triangles, which are then pixel shaded and written to the frame buffer 77. FIG. 7 shows a higher level view of the baseline GPU architecture 70 that matches the API and the programming model while FIG. 8 illustrates a more detailed microarchitecture 80 of the baseline GPU. The GPU may be a unified shader model and may consist of three parts: unslice 81, slice 82 and uncore 85.

In some embodiments, a 3D image may start out as a collection of triangulated surfaces where vertices of the triangles define the shape of the object. An input list of these vertices may be provided to a vertex fetcher (VF) 71 a that in turn fetches the attributes associated with the vertices from memory. In a subsequent vertex shader (VS) 71 b, the fetched attributes of the vertices are transformed using the programmable shaders. For example, a programmable shader may act as a subroutine that maps vertices onto the screen and add special effects to the objects in a 3D environment by performing mathematical operations on their attributes. These shaders are dispatched to the thread processors—referred as execution units (EUs)—where the attributes of vertices like position, color, texture-coordinates etc. are transformed and the computed values are stored in the local memory 82 a for reference by the subsequent pipe stages. The output of the VS unit goes to the next pipeline stages, which may include hull shader (HS) 71 c, tesselation 71 d, and domain shader (DS) 71 e, if applicable, or sent to the primitive assembler 71 g where the triangles (e.g. primitives) are created.

Advantageously, some embodiments of the graphics processor 70 may include a primitive replicator 71 h communicatively coupled to the primitive assembler 71 g to replicate the triangles. In some embodiments, the primitive replicator 71 h may be closely coupled with one or more of the vertex shaders 71 b-e. For example, new API constructs may enable primitive replication at the vertex shaders 71 b-e, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments a graphics driver may include primitive replication commands and the vertex shaders 71 b-e may include logic related to position calculation (e.g., moved from the GS to the VS).

After creation of the triangles and replication of the triangles, a first clipping stage 71 i may discard the triangles that are outside the viewport frustum on a per viewport basis. The triangles that are within the planes of the viewport frustum are accepted and sent to the subsequent pipe stages. Moreover, another clipping stage 71 j may also clip the triangles that intersect with the planes of the view frustum. The triangles that survived the viewport frustum discards and clip operations may yet again be examined by a simple cull stage 71 k to confirm whether the triangle will be part of the final image or not, and the objects that fail these tests may be thrown away (e.g., discarded or disregarded). For example, the back facing, degenerate, zero area etc. triangles may be discarded in the simple cull stage 71 k. As described below, for some applications more than about eighty percent (80%) of the triangles may be discarded either by the viewport frustum clipping stage 71 i or simple cull stage 71 k. Finally, the passing triangles may be sent to a setup unit 72.

Another part of the baseline architecture 70 is the pixel pipe that contains the rasterization 73, stencil and depth 74, the shading and texture 75 and color clusters 76. The pixel pipe begins with the rasterization unit 73 that may determine the location of all the pixels that either lie inside or on the edges of the triangles sent by the geometry pipe 71. Further, it divides the triangles into symmetrical blocks of pixels that may be sent to the depth (Z) pipe 74 for depth test. As multiple objects in the 3D scene can map to the same position, the depth pipe 74 may determine whether the pixels embedded in the block are closest to the observer or are hidden by the previously observed pixels belonging to a different object. The pixels that pass the depth tests may then be shaded (shading and texture unit 75) for determining their color and other attributes related to them. Finally, the computed values of the pixels may be sent to the color pipe 76 that may either optionally blend the computed values with the previously known states or send them to update the frame buffer 77.

As shown in FIG. 8, the geometry pipeline 71 from the vertex fetcher 71 a through the simple cull stage 71 k may be similarly provided as geometry pipeline 81 a in the unslice portion 81 of the microarchitecture 80. The programmable shaders emanating from the geometry pipe 81 a may be dispatched to the local thread processors 82 d via global thread dispatch 81 b and the computed values may be recorded in the local memory 82 a. The passing triangles from the geometry pipe 81 a may be shipped to the slices 82 where they may be divided into symmetrical blocks of pixels via the rasterization walk. The pixel blocks may be hashed via the pixel hashing mechanism 82 b to decide whether the block is going to be rendered in the slice or not. The hashing mechanism 82 b may be responsible not only for the load-balance but also to maintain the pixel-coherency.

As described above, multiple triangles in a 3D scene may overlap and it may be incumbent upon the hashing mechanism 82 b to send the pixel block at a given screen coordinate to the same slice 82 as well as the same compute cluster 82 c via a local thread dispatch 82 d. This may be done in order to maintain the depth and the color coherency of the pixels. Further, the slice portion 82 of the micro architecture may be divided into two functional blocks, namely a pixel pipe 82 e and the compute clusters 82 c. As described above, the pixel pipe 82 e may contain the rasterization, depth and color cluster while the compute cluster 82 c may encompass the array of EUs 82 f used for executing programmable shaders. Each EU 82 f may support multiple thread contexts with different single instruction multiple data (SIMD) widths—i.e. 8, 16 or 32 in one embodiment. Internally, an EU 82 f may have two pipes that are quad-pumped. Each pipe may have four-stream SIMD processors and may execute both floating point and scalar instructions. Each compute cluster 82 c may also have a shared texture-sampling unit 82 g and a load/store unit 82 h that may do gathered reads as well as scattered writes. In addition, the shared functions may have their own private caches backed up by the unified L2 cache 83 as shown in FIG. 8. Finally, similar architecture generations may try to satisfy diverse market segments, for example, from phone/tablet devices to high-end gaming computers. Thus, similar architecture generations might support products that have different numbers of compute clusters 82 c and slices 82.

In some embodiments, the uncore 85 may encompass a cache/memory interface 84, a last level cache(s) (LLCs) 85 a as well as the memory 86. Just like the slices 82, the uncore configuration may also be dependent upon the market segment. For example, high end configurations may have a last level cache along with embedded-dynamic random access memory (eDRAM) 85 b while the configuration for a phone/tablet may have a memory controller and system memory.

Advantageously, some embodiments of the GPU architecture 70 and/or microarchitecture 80 may replicate primitives across multiple viewports with position attribute varying per viewport in single geometry pass. In some embodiments, this feature may enable graphics software to perform operations such as stereo rendering, cube map rendering and cascaded shadow map generation using a single pass thus saving on, for example, repeated vertex shading and tessellation. In some embodiments, this feature may also allow the flexibility of evaluating the positions at different views with an arbitrary transform that can be applied to the original position. For example, some embodiments may allow for arbitrarily computed position attributes to be replicated across multiple viewports.

The following are non-limiting examples of usage scenarios where a same geometry with identical attributes may be projected into different viewports and/or render target array indices, and only the position attribute varies.

1. Stereoscopic rendering: the primitive replicator may replicate primitives into two viewports, one each for left and right eye viewports. For example, each viewport may have different offsets in X/Y directions.

2. Cubemap rendering/voxel lighting: the primitive replicator may map primitives onto all 6 cube faces at once and/or compute light contribution for each of 6 voxel faces at once. For example, each viewport may project onto/from a different plane.

3. Cascaded shadow maps: the primitive replicator may compute shadow maps for multiple inset sections (cascades) with a single geometry pass. In this example, all viewports have unmodified coordinates.

Without being limited to specific implementations, some useful example API features may be provided in accordance with various embodiments. Providing an API feature to replicate primitives across viewports may be useful in applications such as, for example, stereo rendering for 3D TV (e.g. with eye tracking), stereo rendering for virtual reality, cube map generation, and cascaded shadow maps. Providing an API feature to replicate primitives across viewports and render target array indices (RTAI) may be useful in applications such as, for example, cube map generation and cascaded shadow maps. Providing an API feature to apply a position offset may be useful in applications such as, for example, stereo rendering for 3D television (TV) with eye tracking (e.g. for XYW) and stereo rendering for virtual reality (e.g. for X). Providing an API feature to apply a position swizzle may be useful in applications such as, for example, cube map generation (e.g. for XYW). Providing an API feature to apply a position negation may be useful in applications such as, for example, cube map generation. Further details are provided in non-limiting example use cases I, II, and III below.

USE CASE I: Virtual Reality—Left/Right Eye Rendering:

1. Actors: Human w/VR set, VR application, 3D driver/GPU;

2. Goal: Left/right eye image projected on VR set;

3. Example Sequence of Events:

a. Human starts VR application wearing VR set;

b. VR application uses new API to configure 2 viewports in 3D driver;

c. VR application uses new high level shading language (HLSL) construct to compute per-viewport position attributes and broadcast other attributes across viewports;

d. VR application submits one set of draw-calls, common to both eyes; and

e. VR set displays two images, with replicated geometry and shifted per eye view.

USE CASE II: Cube Map Rendering:

1. Actors: 3D application, 3D driver, GPU;

2. Goal: Cube Map rendered in single pass (one draw-call);

3. Example Sequence of Events:

a. 3D application uses new API to configure 6 viewports in 3D driver;

b. 3D application uses new HLSL construct to broadcast geometry across viewports from VS, with different XYZW (e.g. where X, Y, Z are coordinates and W indicates a particular viewport) swizzles and negations (6 cube faces); and

c. 3D application submits one set of draw-calls to generate all 6 cube faces.

USE CASE III: Cascaded Shadow Maps:

1. Actors: 3D application, 3D driver, GPU;

2. Goals: Shadow Map Cascade rendered in single pass (one draw-call);

3. Example Sequence of Events:

a. 3D application uses existing API to configure N viewports in 3D driver, with different height/width;

b. 3D application uses new HLSL construct to broadcast geometry across viewports from VS; and

c. 3D application submits one set of draw-calls to generate all N shadow map cascades in one pass.

Turning now to FIG. 9, some embodiments advantageously may also perform primitive replication in a GPU architecture 90 which includes a position only shading (POSH) pipeline where primitives can be replicated to multiple viewports and discard checks can be performed on them on per view basis and render only such primitives that have at least one view visible in them. Advantageously, some embodiments of the GPU architecture 90 may lower API/driver processing overhead for VR/Stereo applications. Some embodiments of the GPU architecture 90 may exhibit a benefit in GPU performance as compared to an API level replication method and exhibit higher performance as compared to a geometry shader replication method.

The GPU architecture 90 may include two geometry pipes, namely a first geometry pipe referred to as a cull pipe 91 and a second geometry pipe referred to as a replay pipe 93. Both the pipes 91, 93 may execute different instances of the same application where each instance may be working on a completely different draw-call. The responsibility of the cull pipe 91 may be to compute the visibility information of the triangles, whether the triangle is rejected or not. The visibility information determined by the cull pipe 91 may be stored in a visibility recording register 92 (e.g. a first-in-first-out (FIFO) register), which may be communicatively coupled between the cull pipe 91 and the replay pipe 93. The information stored in the visibility register 92 may in turn be consumed by the replay pipe 93 for skipping the discarded triangles. Moreover, the cull pipe 91 may generate this critical information faster by only fetching and shading the position attributes, for example, as a position-only shader. In this way, both the pipes 91, 93 may work together for not only reducing the amount of work required for the culled triangle sequences but also for efficiently skipping them.

The replay pipe 93 may be configured similarly to the pipeline 71 from FIG. 7, including a vertex fetcher 93 a, a vertex shader 93 b, a hull shader 93 c, a tessellation unit 93 d, a domain shader 93 e, and a primitive assembler 93 g. The replay pipe 93 advantageously may further include a primitive replicator 93 h communicatively coupled to the primitive assembler 93 g to replicate the assembled primitives on a per viewport basis. In some embodiments, the primitive replicator 93 h may be closely coupled with one or more of the vertex shaders 93 b-e. For example, new API constructs may enable primitive replication at the vertex shaders 93 b-e, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments a graphics driver may include primitive replication commands and the vertex shaders 93 b-e may include logic related to position calculation (e.g., moved from the GS to the VS). The replay pipe 93 may further include a first culler 93 i to perform view frustum discards, a 3D clipper 93 j to clip triangles which intersect the view frustum, and a simple culler 93 k to perform simple culls on the triangles.

As shown in FIG. 9, the primitive replicator 93 h is provided in the graphics pipeline just after the primitive assembler 93 g. The primitive replicator may be responsible for accepting one input primitive at a time and then generating multiple replicas of the original primitive for each of the programmed viewports with some adjustments made to, for example, the system interpreted values such as a viewport index, a render target array index, and/or a layer index.

The remainder of the graphics pipeline 93 may perform as described earlier by accepting one triangle at a time doing discard tests and culls for one view at a time. Likewise, the GPU architecture 90 may further include a pixel pipe 94 (e.g. including setup unit 94 a, rasterization unit 94 b, stencil and depth unit 94 c, shading and texture unit 94 d, and color blend unit 94 e) and a local memory 95.

As shown in FIG. 9, a similar primitive replicator 91 d is added to the cull pipe 91 also and all the replicas may be generated post primitive assembly. The cull pipe 91 may further include a vertex fetcher 91 a, a vertex shader 91 b, a primitive assembler 91 c, a first culler 91 e to perform visibility tests for the primitives and/or to cull primitives outside the view frustum, and a simple culler 91 f to perform simple culls on the primitives. All the assembled and replicated primitives may undergo viewport discard and simple cull tests. A visibility stream may be recorded per original triangle marking each of the triangles as visible if any replica of the triangle is visible. The visibility stream may record a triangle as not visible only if all the replicas are rejected because of visibility tests.

Alternatively, in some embodiments, the cull pipe 91 may be programmed to have a conservative viewport covering the entire view frustum common to all the views. In this alternative example, the cull pipe 91 may not need to replicate any primitives but may just perform the visibility tests on a per assembled primitive basis and record the visibility stream.

In addition to potential performance improvements, position-only shading also provides opportunity to save power and enhances the scalability of the architecture 90. The resources inside the GPU may be utilized via the cull pipe 91 such that the GPU may complete the computation of critical work faster.

Typically, the shading attributes may include position, normal, color and texture coordinates as examples. In some embodiments when position-only shading is to be implemented, only the position attributes may be read from memory rather than reading all the attributes and then selecting the position attributes out. This saves time, compute cycles and memory bandwidth in some embodiments. Thus in some embodiments, during the vertex fetch, only the position attributes may be fetched by the vertex fetcher 91 a. in some embodiments, the computation of position shaders may be decoupled further in time such that the GPU can effectively hide some cull sequences. A mechanism may “pre-execute” the position shaders and may effectively consume its latency on behalf of the main application such that long running culled sequences can be skipped. In short, a position-only shader may not only realize performance gains but may also saves power by doing less work for discarded vertices in some embodiments.

Some of the pipe stages, such as tessellation and geometry-shader may be omitted from the cull pipe 91, in some embodiments. If a draw call includes tessellation, geometry shader, or other function not implemented in the cull pipe 91, the cull pipe 91 skips that draw call and the replay pipe 93 may handle that draw call a regular manner. For example, the replay pipe 93 may not expect the visibility information for that draw call. To accomplish this, a driver may set a bit in the draw call command indicating whether the command comes into the domain of cull pipe 91 or not. Similarly, there can be conditions when the vertex-only draw calls may require information that is computed via the pixel shaders of the previous draw calls. This may happen very rarely in applications but the driver may still set the bit indicating that these kinds of draw calls will not be handled via the cull pipe 91. The replay pipe 93 includes the discard/clip/cull stages in its pipeline to handle those situations. In some embodiments, the cull pipe 91 may not include a 3D clipper, so the triangles that intersect with the view frustum planes may be treated as passed (e.g. they may be marked as visible in the cull pipe 91). The replay pipe 93 may then handle all of the primitive clipping.

The visibility FIFO 92 may record the information as bitwise sequence for every triangle of a draw call. For example, a zero (0) for the failing triangle and a one (1) for a passing triangle. This information present in the FIFO 92 may be generated via the cull pipe 91 and may be consumed by the replay pipe 93 for skipping the discarded triangles. In some embodiments, the size of the FIFO 92 may govern how far the cull pipe 91 can run ahead, and hence, can impact the performance of the architecture.

In some embodiments, the position-only shading may be disabled. A draw call driver, for example, may selectively choose to enable or disable visibility recording. For example, if there are only a few vertices in the draw call, the overhead associated with visibility recording may not justify the cost of visibility recording in terms of time, memory bandwidth and compute cycles. Other examples where visibility recording may be disabled for a particular draw call include lines and cases where all the vertices in the draw call are known to be visible. When position-only shading is disabled, the replay pipeline may not look for any bitwise information for that draw call and there may be no visibility information for the entire draw call.

The local memory 95 may be used for recording the shaded attributes of the vertices that are referenced both by the discarding logic in the geometry pipes 91, 93 as well as the pixel pipe 94 for rendering pixels. Recall that vertices may have an arbitrary number of attributes like position, normal, color, texture-coordinates, etc. These attributes may be shaded by various vertex shaders and the outcomes may be recorded in the local memory 95 for future reference. The recorded information may be dereferenced whenever it is no longer required. For example, the information may be dereferenced when a triangle is discarded by the culling logic or when all the pixels for a given triangle are rendered. In some embodiments, the local memory 95 may be a free-list of registers that are allocated for a vertex and then returned to the pool when not required.

Culling techniques may improve performance in a graphics processor. Some techniques include backface culling, view frustum culling, Z-max occlusion culling, and occlusion queries. In general, a culling technique reduces the amount of unnecessary work done to render an image, e.g., by discarding triangles that are fully outside the field of view (also called the view frustum in graphics). In general, the earlier culling tests may be preferred in a graphics pipeline because then the data can be discarded in the pipeline earlier, and the costs can be reduced. Z-max occlusion culling may be performed earlier using a position-only shading (POS) pipeline, for example, such as the cull pipe 91.

System Overview

FIG. 10 is a block diagram of a processing system 100, according to an embodiment. In various embodiments the system 100 includes one or more processors 102 and one or more graphics processors 108, and may be a single processor desktop system, a multiprocessor workstation system, or a server system having a large number of processors 102 or processor cores 107. In one embodiment, the system 100 is a processing platform incorporated within a system-on-a-chip (SoC) integrated circuit for use in mobile, handheld, or embedded devices. Advantageously, some embodiments of the processing system 100 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the system 100 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

In one embodiment the system 100 can include, or be incorporated within a server-based gaming platform, a game console, including a game and media console, a mobile gaming console, a handheld game console, or an online game console. In some embodiments the system 100 is a mobile phone, smart phone, tablet computing device or mobile Internet device. The processing system 100 can also include, couple with, or be integrated within a wearable device, such as a smart watch wearable device, smart eyewear device, augmented reality device, or virtual reality device. In some embodiments, the processing system 100 is a television or set top box device having one or more processors 102 and a graphical interface generated by one or more graphics processors 108.

In some embodiments, the one or more processors 102 each include one or more processor cores 107 to process instructions which, when executed, perform operations for system and user software. In some embodiments, each of the one or more processor cores 107 is configured to process a specific instruction set 109. In some embodiments, instruction set 109 may facilitate Complex Instruction Set Computing (CISC), Reduced Instruction Set Computing (RISC), or computing via a Very Long Instruction Word (VLIW). Multiple processor cores 107 may each process a different instruction set 109, which may include instructions to facilitate the emulation of other instruction sets. Processor core 107 may also include other processing devices, such a Digital Signal Processor (DSP).

In some embodiments, the processor 102 includes cache memory 104. Depending on the architecture, the processor 102 can have a single internal cache or multiple levels of internal cache. In some embodiments, the cache memory is shared among various components of the processor 102. In some embodiments, the processor 102 also uses an external cache (e.g., a Level-3 (L3) cache or Last Level Cache (LLC)) (not shown), which may be shared among processor cores 107 using known cache coherency techniques. A register file 106 is additionally included in processor 102 which may include different types of registers for storing different types of data (e.g., integer registers, floating point registers, status registers, and an instruction pointer register). Some registers may be general-purpose registers, while other registers may be specific to the design of the processor 102.

In some embodiments, one or more processor(s) 102 are coupled with one or more interface bus(es) 110 to transmit communication signals such as address, data, or control signals between processor 102 and other components in the system 100. The interface bus 110, in one embodiment, can be a processor bus, such as a version of the Direct Media Interface (DMI) bus. However, processor busses are not limited to the DMI bus, and may include one or more Peripheral Component Interconnect buses (e.g., PCI, PCI Express), memory busses, or other types of interface busses. In one embodiment the processor(s) 102 include an integrated memory controller 116 and a platform controller hub 130. The memory controller 116 facilitates communication between a memory device and other components of the system 100, while the platform controller hub (PCH) 130 provides connections to I/O devices via a local I/O bus.

The memory device 120 can be a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, flash memory device, phase-change memory device, or some other memory device having suitable performance to serve as process memory. In one embodiment the memory device 120 can operate as system memory for the system 100, to store data 122 and instructions 121 for use when the one or more processors 102 executes an application or process. Memory controller 116 also couples with an optional external graphics processor 112, which may communicate with the one or more graphics processors 108 in processors 102 to perform graphics and media operations. In some embodiments a display device 111 can connect to the processor(s) 102. The display device 111 can be one or more of an internal display device, as in a mobile electronic device or a laptop device or an external display device attached via a display interface (e.g., DisplayPort, etc.). In one embodiment the display device 111 can be a head mounted display (HMD) such as a stereoscopic display device for use in virtual reality (VR) applications or augmented reality (AR) applications.

In some embodiments the platform controller hub 130 enables peripherals to connect to memory device 120 and processor 102 via a high-speed I/O bus. The I/O peripherals include, but are not limited to, an audio controller 146, a network controller 134, a firmware interface 128, a wireless transceiver 126, touch sensors 125, a data storage device 124 (e.g., hard disk drive, flash memory, etc.). The data storage device 124 can connect via a storage interface (e.g., SATA) or via a peripheral bus, such as a Peripheral Component Interconnect bus (e.g., PCI, PCI Express). The touch sensors 125 can include touch screen sensors, pressure sensors, or fingerprint sensors. The wireless transceiver 126 can be a Wi-Fi transceiver, a Bluetooth transceiver, or a mobile network transceiver such as a 3G, 4G, or Long Term Evolution (LTE) transceiver. The firmware interface 128 enables communication with system firmware, and can be, for example, a unified extensible firmware interface (UEFI). The network controller 134 can enable a network connection to a wired network. In some embodiments, a high-performance network controller (not shown) couples with the interface bus 110. The audio controller 146, in one embodiment, is a multi-channel high definition audio controller. In one embodiment the system 100 includes an optional legacy I/O controller 140 for coupling legacy (e.g., Personal System 2 (PS/2)) devices to the system. The platform controller hub 130 can also connect to one or more Universal Serial Bus (USB) controllers 142 connect input devices, such as keyboard and mouse 143 combinations, a camera 144, or other USB input devices.

It will be appreciated that the system 100 shown is exemplary and not limiting, as other types of data processing systems that are differently configured may also be used. For example, an instance of the memory controller 116 and platform controller hub 130 may be integrated into a discreet external graphics processor, such as the external graphics processor 112. In one embodiment the platform controller hub 130 and/or memory controller 116 may be external to the one or more processor(s) 102. For example, the system 100 can include an external memory controller 116 and platform controller hub 130, which may be configured as a memory controller hub and peripheral controller hub within a system chipset that is in communication with the processor(s) 102.

FIG. 11 is a block diagram of an embodiment of a processor 200 having one or more processor cores 202A-202N, an integrated memory controller 214, and an integrated graphics processor 208. Those elements of FIG. 11 having the same reference numbers (or names) as the elements of any other figure herein can operate or function in any manner similar to that described elsewhere herein, but are not limited to such. Processor 200 can include additional cores up to and including additional core 202N represented by the dashed lined boxes. Each of processor cores 202A-202N includes one or more internal cache units 204A-204N. In some embodiments each processor core also has access to one or more shared cached units 206. Advantageously, some embodiments of the processor 200 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the processor 200 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

The internal cache units 204A-204N and shared cache units 206 represent a cache memory hierarchy within the processor 200. The cache memory hierarchy may include at least one level of instruction and data cache within each processor core and one or more levels of shared mid-level cache, such as a Level 2 (L2), Level 3 (L3), Level 4 (L4), or other levels of cache, where the highest level of cache before external memory is classified as the LLC. In some embodiments, cache coherency logic maintains coherency between the various cache units 206 and 204A-204N.

In some embodiments, processor 200 may also include a set of one or more bus controller units 216 and a system agent core 210. The one or more bus controller units 216 manage a set of peripheral buses, such as one or more PCI or PCI express busses. System agent core 210 provides management functionality for the various processor components. In some embodiments, system agent core 210 includes one or more integrated memory controllers 214 to manage access to various external memory devices (not shown).

In some embodiments, one or more of the processor cores 202A-202N include support for simultaneous multi-threading. In such embodiment, the system agent core 210 includes components for coordinating and operating cores 202A-202N during multi-threaded processing. System agent core 210 may additionally include a power control unit (PCU), which includes logic and components to regulate the power state of processor cores 202A-202N and graphics processor 208.

In some embodiments, processor 200 additionally includes graphics processor 208 to execute graphics processing operations. In some embodiments, the graphics processor 208 couples with the set of shared cache units 206, and the system agent core 210, including the one or more integrated memory controllers 214. In some embodiments, the system agent core 210 also includes a display controller 211 to drive graphics processor output to one or more coupled displays. In some embodiments, display controller 211 may also be a separate module coupled with the graphics processor via at least one interconnect, or may be integrated within the graphics processor 208.

In some embodiments, a ring based interconnect unit 212 is used to couple the internal components of the processor 200. However, an alternative interconnect unit may be used, such as a point-to-point interconnect, a switched interconnect, or other techniques, including techniques well known in the art. In some embodiments, graphics processor 208 couples with the ring interconnect 212 via an I/O link 213.

The exemplary I/O link 213 represents at least one of multiple varieties of I/O interconnects, including an on package I/O interconnect which facilitates communication between various processor components and a high-performance embedded memory module 218, such as an eDRAM module. In some embodiments, each of the processor cores 202A-202N and graphics processor 208 use embedded memory modules 218 as a shared Last Level Cache.

In some embodiments, processor cores 202A-202N are homogenous cores executing the same instruction set architecture. In another embodiment, processor cores 202A-202N are heterogeneous in terms of instruction set architecture (ISA), where one or more of processor cores 202A-202N execute a first instruction set, while at least one of the other cores executes a subset of the first instruction set or a different instruction set. In one embodiment processor cores 202A-202N are heterogeneous in terms of microarchitecture, where one or more cores having a relatively higher power consumption couple with one or more power cores having a lower power consumption. Additionally, processor 200 can be implemented on one or more chips or as an SoC integrated circuit having the illustrated components, in addition to other components.

FIG. 12 is a block diagram of a graphics processor 300, which may be a discrete graphics processing unit, or may be a graphics processor integrated with a plurality of processing cores. In some embodiments, the graphics processor communicates via a memory mapped I/O interface to registers on the graphics processor and with commands placed into the processor memory. In some embodiments, graphics processor 300 includes a memory interface 314 to access memory. Memory interface 314 can be an interface to local memory, one or more internal caches, one or more shared external caches, and/or to system memory. Advantageously, some embodiments of the processor 300 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the processor 300 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

In some embodiments, graphics processor 300 also includes a display controller 302 to drive display output data to a display device 320. Display controller 302 includes hardware for one or more overlay planes for the display and composition of multiple layers of video or user interface elements. The display device 320 can be an internal or external display device. In one embodiment the display device 320 is a head mounted display device, such as a virtual reality (VR) display device or an augmented reality (AR) display device. In some embodiments, graphics processor 300 includes a video codec engine 306 to encode, decode, or transcode media to, from, or between one or more media encoding formats, including, but not limited to Moving Picture Experts Group (MPEG) formats such as MPEG-2, Advanced Video Coding (AVC) formats such as H.264/MPEG-4 AVC, as well as the Society of Motion Picture & Television Engineers (SMPTE) 421M/VC-1, and Joint Photographic Experts Group (JPEG) formats such as JPEG, and Motion JPEG (MJPEG) formats.

In some embodiments, graphics processor 300 includes a block image transfer (BLIT) engine 304 to perform two-dimensional (2D) rasterizer operations including, for example, bit-boundary block transfers. However, in one embodiment, 2D graphics operations are performed using one or more components of graphics processing engine (GPE) 310. In some embodiments, GPE 310 is a compute engine for performing graphics operations, including three-dimensional (3D) graphics operations and media operations.

In some embodiments, GPE 310 includes a 3D pipeline 312 for performing 3D operations, such as rendering three-dimensional images and scenes using processing functions that act upon 3D primitive shapes (e.g., rectangle, triangle, etc.). The 3D pipeline 312 includes programmable and fixed function elements that perform various tasks within the element and/or spawn execution threads to a 3D/Media sub-system 315. While 3D pipeline 312 can be used to perform media operations, an embodiment of GPE 310 also includes a media pipeline 316 that is specifically used to perform media operations, such as video post-processing and image enhancement.

In some embodiments, media pipeline 316 includes fixed function or programmable logic units to perform one or more specialized media operations, such as video decode acceleration, video de-interlacing, and video encode acceleration in place of, or on behalf of video codec engine 306. In some embodiments, media pipeline 316 additionally includes a thread spawning unit to spawn threads for execution on 3D/Media sub-system 315. The spawned threads perform computations for the media operations on one or more graphics execution units included in 3D/Media sub-system 315.

In some embodiments, 3D/Media subsystem 315 includes logic for executing threads spawned by 3D pipeline 312 and media pipeline 316. In one embodiment, the pipelines send thread execution requests to 3D/Media subsystem 315, which includes thread dispatch logic for arbitrating and dispatching the various requests to available thread execution resources. The execution resources include an array of graphics execution units to process the 3D and media threads. In some embodiments, 3D/Media subsystem 315 includes one or more internal caches for thread instructions and data. In some embodiments, the subsystem also includes shared memory, including registers and addressable memory, to share data between threads and to store output data.

Graphics Processing Engine

FIG. 13 is a block diagram of a graphics processing engine 410 of a graphics processor in accordance with some embodiments. In one embodiment, the graphics processing engine (GPE) 410 is a version of the GPE 310 shown in FIG. 12. Elements of FIG. 13 having the same reference numbers (or names) as the elements of any other figure herein can operate or function in any manner similar to that described elsewhere herein, but are not limited to such. For example, the 3D pipeline 312 and media pipeline 316 of FIG. 12 are illustrated. The media pipeline 316 is optional in some embodiments of the GPE 410 and may not be explicitly included within the GPE 410. For example and in at least one embodiment, a separate media and/or image processor is coupled to the GPE 410. Advantageously, some embodiments of the GPE 410 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the GPE 410 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

In some embodiments, GPE 410 couples with or includes a command streamer 403, which provides a command stream to the 3D pipeline 312 and/or media pipelines 316. In some embodiments, command streamer 403 is coupled with memory, which can be system memory, or one or more of internal cache memory and shared cache memory. In some embodiments, command streamer 403 receives commands from the memory and sends the commands to 3D pipeline 312 and/or media pipeline 316. The commands are directives fetched from a ring buffer, which stores commands for the 3D pipeline 312 and media pipeline 316. In one embodiment, the ring buffer can additionally include batch command buffers storing batches of multiple commands. The commands for the 3D pipeline 312 can also include references to data stored in memory, such as but not limited to vertex and geometry data for the 3D pipeline 312 and/or image data and memory objects for the media pipeline 316. The 3D pipeline 312 and media pipeline 316 process the commands and data by performing operations via logic within the respective pipelines or by dispatching one or more execution threads to a graphics core array 414. In one embodiment the graphics core array 414 include one or more blocks of graphics cores (e.g., graphics core(s) 415A, graphics core(s) 415B), each block including one or more graphics cores. Each graphics core includes a set of graphics execution resources that includes general-purpose and graphics specific execution logic to perform graphics and compute operations, as well as fixed function texture processing and/or machine learning and artificial intelligence acceleration logic.

In various embodiments the 3D pipeline 312 includes fixed function and programmable logic to process one or more shader programs, such as vertex shaders, geometry shaders, pixel shaders, fragment shaders, compute shaders, or other shader programs, by processing the instructions and dispatching execution threads to the graphics core array 414. The graphics core array 414 provides a unified block of execution resources for use in processing these shader programs. Multi-purpose execution logic (e.g., execution units) within the graphics core(s) 415A-414B of the graphic core array 414 includes support for various 3D API shader languages and can execute multiple simultaneous execution threads associated with multiple shaders.

In some embodiments the graphics core array 414 also includes execution logic to perform media functions, such as video and/or image processing. In one embodiment, the execution units additionally include general-purpose logic that is programmable to perform parallel general-purpose computational operations, in addition to graphics processing operations. The general-purpose logic can perform processing operations in parallel or in conjunction with general-purpose logic within the processor core(s) 107 of FIG. 10 or core 202A-202N as in FIG. 11.

Output data generated by threads executing on the graphics core array 414 can output data to memory in a unified return buffer (URB) 418. The URB 418 can store data for multiple threads. In some embodiments the URB 418 may be used to send data between different threads executing on the graphics core array 414. In some embodiments the URB 418 may additionally be used for synchronization between threads on the graphics core array and fixed function logic within the shared function logic 420.

In some embodiments, graphics core array 414 is scalable, such that the array includes a variable number of graphics cores, each having a variable number of execution units based on the target power and performance level of GPE 410. In one embodiment the execution resources are dynamically scalable, such that execution resources may be enabled or disabled as needed.

The graphics core array 414 couples with shared function logic 420 that includes multiple resources that are shared between the graphics cores in the graphics core array. The shared functions within the shared function logic 420 are hardware logic units that provide specialized supplemental functionality to the graphics core array 414. In various embodiments, shared function logic 420 includes but is not limited to sampler 421, math 422, and inter-thread communication (ITC) 423 logic. Additionally, some embodiments implement one or more cache(s) 425 within the shared function logic 420.

A shared function is implemented where the demand for a given specialized function is insufficient for inclusion within the graphics core array 414. Instead a single instantiation of that specialized function is implemented as a stand-alone entity in the shared function logic 420 and shared among the execution resources within the graphics core array 414. The precise set of functions that are shared between the graphics core array 414 and included within the graphics core array 414 varies across embodiments. In some embodiments, specific shared functions within the shared function logic 420 that are used extensively by the graphics core array 414 may be included within shared function logic 416 within the graphics core array 414. In various embodiments, the shared function logic 416 within the graphics core array 414 can include some or all logic within the shared function logic 420. In one embodiment, all logic elements within the shared function logic 420 may be duplicated within the shared function logic 416 of the graphics core array 414. In one embodiment the shared function logic 420 is excluded in favor of the shared function logic 416 within the graphics core array 414.

FIG. 14 is a block diagram of hardware logic of a graphics processor core 500, according to some embodiments described herein. Elements of FIG. 14 having the same reference numbers (or names) as the elements of any other figure herein can operate or function in any manner similar to that described elsewhere herein, but are not limited to such. The illustrated graphics processor core 500, in some embodiments, is included within the graphics core array 414 of FIG. 13. The graphics processor core 500, sometimes referred to as a core slice, can be one or multiple graphics cores within a modular graphics processor. The graphics processor core 500 is exemplary of one graphics core slice, and a graphics processor as described herein may include multiple graphics core slices based on target power and performance envelopes. Each graphics processor core 500 can include a fixed function block 530 coupled with multiple sub-cores 501A-501F, also referred to as sub-slices, that include modular blocks of general-purpose and fixed function logic. Advantageously, some embodiments of the processor 500 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the processor 500 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

In some embodiments the fixed function block 530 includes a geometry/fixed function pipeline 536 that can be shared by all sub-cores in the graphics processor core 500, for example, in lower performance and/or lower power graphics processor implementations. In various embodiments, the geometry/fixed function pipeline 536 includes a 3D fixed function pipeline (e.g., 3D pipeline 312 as in FIG. 12 and FIG. 13) a video front-end unit, a thread spawner and thread dispatcher, and a unified return buffer manager, which manages unified return buffers, such as the unified return buffer 418 of FIG. 13.

In one embodiment the fixed function block 530 also includes a graphics SoC interface 537, a graphics microcontroller 538, and a media pipeline 539. The graphics SoC interface 537 provides an interface between the graphics processor core 500 and other processor cores within a system on a chip integrated circuit. The graphics microcontroller 538 is a programmable sub-processor that is configurable to manage various functions of the graphics processor core 500, including thread dispatch, scheduling, and pre-emption. The media pipeline 539 (e.g., media pipeline 316 of FIG. 12 and FIG. 13) includes logic to facilitate the decoding, encoding, pre-processing, and/or post-processing of multimedia data, including image and video data. The media pipeline 539 implement media operations via requests to compute or sampling logic within the sub-cores 501-501F.

In one embodiment the SoC interface 537 enables the graphics processor core 500 to communicate with general-purpose application processor cores (e.g., CPUs) and/or other components within an SoC, including memory hierarchy elements such as a shared last level cache memory, the system RAM, and/or embedded on-chip or on-package DRAM. The SoC interface 537 can also enable communication with fixed function devices within the SoC, such as camera imaging pipelines, and enables the use of and/or implements global memory atomics that may be shared between the graphics processor core 500 and CPUs within the SoC. The SoC interface 537 can also implement power management controls for the graphics processor core 500 and enable an interface between a clock domain of the graphic core 500 and other clock domains within the SoC. In one embodiment the SoC interface 537 enables receipt of command buffers from a command streamer and global thread dispatcher that are configured to provide commands and instructions to each of one or more graphics cores within a graphics processor. The commands and instructions can be dispatched to the media pipeline 539, when media operations are to be performed, or a geometry and fixed function pipeline (e.g., geometry and fixed function pipeline 536, geometry and fixed function pipeline 514) when graphics processing operations are to be performed.

The graphics microcontroller 538 can be configured to perform various scheduling and management tasks for the graphics processor core 500. In one embodiment the graphics microcontroller 538 can perform graphics and/or compute workload scheduling on the various graphics parallel engines within execution unit (EU) arrays 502A-502F, 504A-504F within the sub-cores 501A-501F. In this scheduling model, host software executing on a CPU core of an SoC including the graphics processor core 500 can submit workloads one of multiple graphic processor doorbells, which invokes a scheduling operation on the appropriate graphics engine. Scheduling operations include determining which workload to run next, submitting a workload to a command streamer, pre-empting existing workloads running on an engine, monitoring progress of a workload, and notifying host software when a workload is complete. In one embodiment the graphics microcontroller 538 can also facilitate low-power or idle states for the graphics processor core 500, providing the graphics processor core 500 with the ability to save and restore registers within the graphics processor core 500 across low-power state transitions independently from the operating system and/or graphics driver software on the system.

The graphics processor core 500 may have greater than or fewer than the illustrated sub-cores 501A-501F, up to N modular sub-cores. For each set of N sub-cores, the graphics processor core 500 can also include shared function logic 510, shared and/or cache memory 512, a geometry/fixed function pipeline 514, as well as additional fixed function logic 516 to accelerate various graphics and compute processing operations. The shared function logic 510 can include logic units associated with the shared function logic 420 of FIG. 13 (e.g., sampler, math, and/or inter-thread communication logic) that can be shared by each N sub-cores within the graphics processor core 500. The shared and/or cache memory 512 can be a last-level cache for the set of N sub-cores 501A-501F within the graphics processor core 500, and can also serve as shared memory that is accessible by multiple sub-cores. The geometry/fixed function pipeline 514 can be included instead of the geometry/fixed function pipeline 536 within the fixed function block 530 and can include the same or similar logic units.

In one embodiment the graphics processor core 500 includes additional fixed function logic 516 that can include various fixed function acceleration logic for use by the graphics processor core 500. In one embodiment the additional fixed function logic 516 includes an additional geometry pipeline for use in position only shading. In position-only shading, two geometry pipelines exist, the full geometry pipeline within the geometry/fixed function pipeline 516, 536, and a cull pipeline, which is an additional geometry pipeline which may be included within the additional fixed function logic 516. In one embodiment the cull pipeline is a trimmed down version of the full geometry pipeline. The full pipeline and the cull pipeline can execute different instances of the same application, each instance having a separate context. Position only shading can hide long cull runs of discarded triangles, enabling shading to be completed earlier in some instances. For example and in one embodiment the cull pipeline logic within the additional fixed function logic 516 can execute position shaders in parallel with the main application and generally generates critical results faster than the full pipeline, as the cull pipeline fetches and shades only the position attribute of the vertices, without performing rasterization and rendering of the pixels to the frame buffer. The cull pipeline can use the generated critical results to compute visibility information for all the triangles without regard to whether those triangles are culled. The full pipeline (which in this instance may be referred to as a replay pipeline) can consume the visibility information to skip the culled triangles to shade only the visible triangles that are finally passed to the rasterization phase.

In one embodiment the additional fixed function logic 516 can also include machine-learning acceleration logic, such as fixed function matrix multiplication logic, for implementations including optimizations for machine learning training or inferencing.

Within each graphics sub-core 501A-501F includes a set of execution resources that may be used to perform graphics, media, and compute operations in response to requests by graphics pipeline, media pipeline, or shader programs. The graphics sub-cores 501A-501F include multiple EU arrays 502A-502F, 504A-504F, thread dispatch and inter-thread communication (TD/IC) logic 503A-503F, a 3D (e.g., texture) sampler 505A-505F, a media sampler 506A-506F, a shader processor 507A-507F, and shared local memory (SLM) 508A-508F. The EU arrays 502A-502F, 504A-504F each include multiple execution units, which are general-purpose graphics processing units capable of performing floating-point and integer/fixed-point logic operations in service of a graphics, media, or compute operation, including graphics, media, or compute shader programs. The TD/IC logic 503A-503F performs local thread dispatch and thread control operations for the execution units within a sub-core and facilitate communication between threads executing on the execution units of the sub-core. The 3D sampler 505A-505F can read texture or other 3D graphics related data into memory. The 3D sampler can read texture data differently based on a configured sample state and the texture format associated with a given texture. The media sampler 506A-506F can perform similar read operations based on the type and format associated with media data. In one embodiment, each graphics sub-core 501A-501F can alternately include a unified 3D and media sampler. Threads executing on the execution units within each of the sub-cores 501A-501F can make use of shared local memory 508A-508F within each sub-core, to enable threads executing within a thread group to execute using a common pool of on-chip memory.

Execution Units

FIGS. 15A-15B illustrate thread execution logic 600 including an array of processing elements employed in a graphics processor core according to embodiments described herein. Elements of FIGS. 15A-15B having the same reference numbers (or names) as the elements of any other figure herein can operate or function in any manner similar to that described elsewhere herein, but are not limited to such. FIG. 15A illustrates an overview of thread execution logic 600, which can include a variant of the hardware logic illustrated with each sub-core 501A-501F of FIG. 14. FIG. 15B illustrates exemplary internal details of an execution unit.

As illustrated in FIG. 15A, in some embodiments thread execution logic 600 includes a shader processor 602, a thread dispatcher 604, instruction cache 606, a scalable execution unit array including a plurality of execution units 608A-608N, a sampler 610, a data cache 612, and a data port 614. In one embodiment the scalable execution unit array can dynamically scale by enabling or disabling one or more execution units (e.g., any of execution unit 608A, 608B, 608C, 608D, through 608N-1 and 608N) based on the computational requirements of a workload. In one embodiment the included components are interconnected via an interconnect fabric that links to each of the components. In some embodiments, thread execution logic 600 includes one or more connections to memory, such as system memory or cache memory, through one or more of instruction cache 606, data port 614, sampler 610, and execution units 608A-608N. In some embodiments, each execution unit (e.g. 608A) is a stand-alone programmable general-purpose computational unit that is capable of executing multiple simultaneous hardware threads while processing multiple data elements in parallel for each thread. In various embodiments, the array of execution units 608A-608N is scalable to include any number individual execution units.

In some embodiments, the execution units 608A-608N are primarily used to execute shader programs. A shader processor 602 can process the various shader programs and dispatch execution threads associated with the shader programs via a thread dispatcher 604. In one embodiment the thread dispatcher includes logic to arbitrate thread initiation requests from the graphics and media pipelines and instantiate the requested threads on one or more execution unit in the execution units 608A-608N. For example, a geometry pipeline can dispatch vertex, tessellation, or geometry shaders to the thread execution logic for processing. In some embodiments, thread dispatcher 604 can also process runtime thread spawning requests from the executing shader programs.

In some embodiments, the execution units 608A-608N support an instruction set that includes native support for many standard 3D graphics shader instructions, such that shader programs from graphics libraries (e.g., Direct 3D and OpenGL) are executed with a minimal translation. The execution units support vertex and geometry processing (e.g., vertex programs, geometry programs, vertex shaders), pixel processing (e.g., pixel shaders, fragment shaders) and general-purpose processing (e.g., compute and media shaders). Each of the execution units 608A-608N is capable of multi-issue single instruction multiple data (SIMD) execution and multi-threaded operation enables an efficient execution environment in the face of higher latency memory accesses. Each hardware thread within each execution unit has a dedicated high-bandwidth register file and associated independent thread-state. Execution is multi-issue per clock to pipelines capable of integer, single and double precision floating point operations, SIMD branch capability, logical operations, transcendental operations, and other miscellaneous operations. While waiting for data from memory or one of the shared functions, dependency logic within the execution units 608A-608N causes a waiting thread to sleep until the requested data has been returned. While the waiting thread is sleeping, hardware resources may be devoted to processing other threads. For example, during a delay associated with a vertex shader operation, an execution unit can perform operations for a pixel shader, fragment shader, or another type of shader program, including a different vertex shader.

Each execution unit in execution units 608A-608N operates on arrays of data elements. The number of data elements is the “execution size,” or the number of channels for the instruction. An execution channel is a logical unit of execution for data element access, masking, and flow control within instructions. The number of channels may be independent of the number of physical Arithmetic Logic Units (ALUs) or Floating Point Units (FPUs) for a particular graphics processor. In some embodiments, execution units 608A-608N support integer and floating-point data types.

The execution unit instruction set includes SIMD instructions. The various data elements can be stored as a packed data type in a register and the execution unit will process the various elements based on the data size of the elements. For example, when operating on a 256-bit wide vector, the 256 bits of the vector are stored in a register and the execution unit operates on the vector as four separate 64-bit packed data elements (Quad-Word (QW) size data elements), eight separate 32-bit packed data elements (Double Word (DW) size data elements), sixteen separate 16-bit packed data elements (Word (W) size data elements), or thirty-two separate 8-bit data elements (byte (B) size data elements). However, different vector widths and register sizes are possible.

In one embodiment one or more execution units can be combined into a fused execution unit 609A-609N having thread control logic (607A-607N) that is common to the fused EUs. Multiple EUs can be fused into an EU group. Each EU in the fused EU group can be configured to execute a separate SIMD hardware thread. The number of EUs in a fused EU group can vary according to embodiments. Additionally, various SIMD widths can be performed per-EU, including but not limited to SIMD8, SIMD16, and SIMD32. Each fused graphics execution unit 609A-609N includes at least two execution units. For example, fused execution unit 609A includes a first EU 608A, second EU 608B, and thread control logic 607A that is common to the first EU 608A and the second EU 608B. The thread control logic 607A controls threads executed on the fused graphics execution unit 609A, allowing each EU within the fused execution units 609A-609N to execute using a common instruction pointer register.

One or more internal instruction caches (e.g., 606) are included in the thread execution logic 600 to cache thread instructions for the execution units. In some embodiments, one or more data caches (e.g., 612) are included to cache thread data during thread execution. In some embodiments, a sampler 610 is included to provide texture sampling for 3D operations and media sampling for media operations. In some embodiments, sampler 610 includes specialized texture or media sampling functionality to process texture or media data during the sampling process before providing the sampled data to an execution unit.

During execution, the graphics and media pipelines send thread initiation requests to thread execution logic 600 via thread spawning and dispatch logic. Once a group of geometric objects has been processed and rasterized into pixel data, pixel processor logic (e.g., pixel shader logic, fragment shader logic, etc.) within the shader processor 602 is invoked to further compute output information and cause results to be written to output surfaces (e.g., color buffers, depth buffers, stencil buffers, etc.). In some embodiments, a pixel shader or fragment shader calculates the values of the various vertex attributes that are to be interpolated across the rasterized object. In some embodiments, pixel processor logic within the shader processor 602 then executes an application programming interface (API)-supplied pixel or fragment shader program. To execute the shader program, the shader processor 602 dispatches threads to an execution unit (e.g., 608A) via thread dispatcher 604. In some embodiments, shader processor 602 uses texture sampling logic in the sampler 610 to access texture data in texture maps stored in memory. Arithmetic operations on the texture data and the input geometry data compute pixel color data for each geometric fragment, or discards one or more pixels from further processing.

In some embodiments, the data port 614 provides a memory access mechanism for the thread execution logic 600 to output processed data to memory for further processing on a graphics processor output pipeline. In some embodiments, the data port 614 includes or couples to one or more cache memories (e.g., data cache 612) to cache data for memory access via the data port.

As illustrated in FIG. 15B, a graphics execution unit 608 can include an instruction fetch unit 637, a general register file array (GRF) 624, an architectural register file array (ARF) 626, a thread arbiter 622, a send unit 630, a branch unit 632, a set of SIMD floating point units (FPUs) 634, and in one embodiment a set of dedicated integer SIMD ALUs 635. The GRF 624 and ARF 626 includes the set of general register files and architecture register files associated with each simultaneous hardware thread that may be active in the graphics execution unit 608. In one embodiment, per thread architectural state is maintained in the ARF 626, while data used during thread execution is stored in the GRF 624. The execution state of each thread, including the instruction pointers for each thread, can be held in thread-specific registers in the ARF 626.

In one embodiment the graphics execution unit 608 has an architecture that is a combination of Simultaneous Multi-Threading (SMT) and fine-grained Interleaved Multi-Threading (IMT). The architecture has a modular configuration that can be fine tuned at design time based on a target number of simultaneous threads and number of registers per execution unit, where execution unit resources are divided across logic used to execute multiple simultaneous threads.

In one embodiment, the graphics execution unit 608 can co-issue multiple instructions, which may each be different instructions. The thread arbiter 622 of the graphics execution unit thread 608 can dispatch the instructions to one of the send unit 630, branch unit 632, or SIMD FPU(s) 634 for execution. Each execution thread can access 128 general-purpose registers within the GRF 624, where each register can store 32 bytes, accessible as a SIMD 8-element vector of 32-bit data elements. In one embodiment, each execution unit thread has access to 4 Kbytes within the GRF 624, although embodiments are not so limited, and greater or fewer register resources may be provided in other embodiments. In one embodiment up to seven threads can execute simultaneously, although the number of threads per execution unit can also vary according to embodiments. In an embodiment in which seven threads may access 4 Kbytes, the GRF 624 can store a total of 28 Kbytes. Flexible addressing modes can permit registers to be addressed together to build effectively wider registers or to represent strided rectangular block data structures.

In one embodiment, memory operations, sampler operations, and other longer-latency system communications are dispatched via “send” instructions that are executed by the message passing send unit 630. In one embodiment, branch instructions are dispatched to a dedicated branch unit 632 to facilitate SIMD divergence and eventual convergence.

In one embodiment the graphics execution unit 608 includes one or more SIMD floating point units (FPU(s)) 634 to perform floating-point operations. In one embodiment, the FPU(s) 634 also support integer computation. In one embodiment the FPU(s) 634 can SIMD execute up to M number of 32-bit floating-point (or integer) operations, or SIMD execute up to 2M 16-bit integer or 16-bit floating-point operations. In one embodiment, at least one of the FPU(s) provides extended math capability to support high-throughput transcendental math functions and double precision 64-bit floating-point. In some embodiments, a set of 8-bit integer SIMD ALUs 635 are also present, and may be specifically optimized to perform operations associated with machine learning computations.

In one embodiment, arrays of multiple instances of the graphics execution unit 608 can be instantiated in a graphics sub-core grouping (e.g., a sub-slice). For scalability, product architects can chose the exact number of execution units per sub-core grouping. In one embodiment the execution unit 608 can execute instructions across a plurality of execution channels. In a further embodiment, each thread executed on the graphics execution unit 608 is executed on a different channel.

FIG. 16 is a block diagram illustrating a graphics processor instruction formats 700 according to some embodiments. In one or more embodiment, the graphics processor execution units support an instruction set having instructions in multiple formats. The solid lined boxes illustrate the components that are generally included in an execution unit instruction, while the dashed lines include components that are optional or that are only included in a sub-set of the instructions. In some embodiments, instruction format 700 described and illustrated are macro-instructions, in that they are instructions supplied to the execution unit, as opposed to micro-operations resulting from instruction decode once the instruction is processed.

In some embodiments, the graphics processor execution units natively support instructions in a 128-bit instruction format 710. A 64-bit compacted instruction format 730 is available for some instructions based on the selected instruction, instruction options, and number of operands. The native 128-bit instruction format 710 provides access to all instruction options, while some options and operations are restricted in the 64-bit format 730. The native instructions available in the 64-bit format 730 vary by embodiment. In some embodiments, the instruction is compacted in part using a set of index values in an index field 713. The execution unit hardware references a set of compaction tables based on the index values and uses the compaction table outputs to reconstruct a native instruction in the 128-bit instruction format 710.

For each format, instruction opcode 712 defines the operation that the execution unit is to perform. The execution units execute each instruction in parallel across the multiple data elements of each operand. For example, in response to an add instruction the execution unit performs a simultaneous add operation across each color channel representing a texture element or picture element. By default, the execution unit performs each instruction across all data channels of the operands. In some embodiments, instruction control field 714 enables control over certain execution options, such as channels selection (e.g., predication) and data channel order (e.g., swizzle). For instructions in the 128-bit instruction format 710 an exec-size field 716 limits the number of data channels that will be executed in parallel. In some embodiments, exec-size field 716 is not available for use in the 64-bit compact instruction format 730.

Some execution unit instructions have up to three operands including two source operands, src0 720, src1 722, and one destination 718. In some embodiments, the execution units support dual destination instructions, where one of the destinations is implied. Data manipulation instructions can have a third source operand (e.g., SRC2 724), where the instruction opcode 712 determines the number of source operands. An instruction's last source operand can be an immediate (e.g., hard-coded) value passed with the instruction.

In some embodiments, the 128-bit instruction format 710 includes an access/address mode field 726 specifying, for example, whether direct register addressing mode or indirect register addressing mode is used. When direct register addressing mode is used, the register address of one or more operands is directly provided by bits in the instruction.

In some embodiments, the 128-bit instruction format 710 includes an access/address mode field 726, which specifies an address mode and/or an access mode for the instruction. In one embodiment the access mode is used to define a data access alignment for the instruction. Some embodiments support access modes including a 16-byte aligned access mode and a 1-byte aligned access mode, where the byte alignment of the access mode determines the access alignment of the instruction operands. For example, when in a first mode, the instruction may use byte-aligned addressing for source and destination operands and when in a second mode, the instruction may use 16-byte-aligned addressing for all source and destination operands.

In one embodiment, the address mode portion of the access/address mode field 726 determines whether the instruction is to use direct or indirect addressing. When direct register addressing mode is used bits in the instruction directly provide the register address of one or more operands. When indirect register addressing mode is used, the register address of one or more operands may be computed based on an address register value and an address immediate field in the instruction.

In some embodiments instructions are grouped based on opcode 712 bit-fields to simplify Opcode decode 740. For an 8-bit opcode, bits 4, 5, and 6 allow the execution unit to determine the type of opcode. The precise opcode grouping shown is merely an example. In some embodiments, a move and logic opcode group 742 includes data movement and logic instructions (e.g., move (mov), compare (cmp)). In some embodiments, move and logic group 742 shares the five most significant bits (MSB), where move (mov) instructions are in the form of 0000xxxxb and logic instructions are in the form of 0001xxxxb. A flow control instruction group 744 (e.g., call, jump (jmp)) includes instructions in the form of 0010xxxxb (e.g., 0x20). A miscellaneous instruction group 746 includes a mix of instructions, including synchronization instructions (e.g., wait, send) in the form of 0011xxxxb (e.g., 0x30). A parallel math instruction group 748 includes component-wise arithmetic instructions (e.g., add, multiply (mul)) in the form of 0100xxxxb (e.g., 0x40). The parallel math group 748 performs the arithmetic operations in parallel across data channels. The vector math group 750 includes arithmetic instructions (e.g., dp4) in the form of 0101xxxxb (e.g., 0x50). The vector math group performs arithmetic such as dot product calculations on vector operands.

Graphics Pipeline

FIG. 17 is a block diagram of another embodiment of a graphics processor 800. Elements of FIG. 17 having the same reference numbers (or names) as the elements of any other figure herein can operate or function in any manner similar to that described elsewhere herein, but are not limited to such. Advantageously, some embodiments of the processor 300 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the processor 300 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

In some embodiments, graphics processor 800 includes a geometry pipeline 820, a media pipeline 830, a display engine 840, thread execution logic 850, and a render output pipeline 870. In some embodiments, graphics processor 800 is a graphics processor within a multi-core processing system that includes one or more general-purpose processing cores. The graphics processor is controlled by register writes to one or more control registers (not shown) or via commands issued to graphics processor 800 via a ring interconnect 802. In some embodiments, ring interconnect 802 couples graphics processor 800 to other processing components, such as other graphics processors or general-purpose processors. Commands from ring interconnect 802 are interpreted by a command streamer 803, which supplies instructions to individual components of the geometry pipeline 820 or the media pipeline 830.

In some embodiments, command streamer 803 directs the operation of a vertex fetcher 805 that reads vertex data from memory and executes vertex-processing commands provided by command streamer 803. In some embodiments, vertex fetcher 805 provides vertex data to a vertex shader 807, which performs coordinate space transformation and lighting operations to each vertex. In some embodiments, vertex fetcher 805 and vertex shader 807 execute vertex-processing instructions by dispatching execution threads to execution units 852A-852B via a thread dispatcher 831.

In some embodiments, execution units 852A-852B are an array of vector processors having an instruction set for performing graphics and media operations. In some embodiments, execution units 852A-852B have an attached L1 cache 851 that is specific for each array or shared between the arrays. The cache can be configured as a data cache, an instruction cache, or a single cache that is partitioned to contain data and instructions in different partitions.

In some embodiments, geometry pipeline 820 includes tessellation components to perform hardware-accelerated tessellation of 3D objects. In some embodiments, a programmable hull shader 811 configures the tessellation operations. A programmable domain shader 817 provides back-end evaluation of tessellation output. A tessellator 813 operates at the direction of hull shader 811 and contains special purpose logic to generate a set of detailed geometric objects based on a coarse geometric model that is provided as input to geometry pipeline 820. In some embodiments, if tessellation is not used, tessellation components (e.g., hull shader 811, tessellator 813, and domain shader 817) can be bypassed.

In some embodiments, complete geometric objects can be processed by a geometry shader 819 via one or more threads dispatched to execution units 852A-852B, or can proceed directly to the clipper 829. In some embodiments, the geometry shader operates on entire geometric objects, rather than vertices or patches of vertices as in previous stages of the graphics pipeline. If the tessellation is disabled the geometry shader 819 receives input from the vertex shader 807. In some embodiments, geometry shader 819 is programmable by a geometry shader program to perform geometry tessellation if the tessellation units are disabled. As discussed in detail above, if conditions permit the geometry shader may be omitted or bypassed and primitive replication and various geometry shader logic may be moved to the vertex shader.

Before rasterization, a clipper 829 processes vertex data. The clipper 829 may be a fixed function clipper or a programmable clipper having clipping and geometry shader functions. In some embodiments, a rasterizer and depth test component 873 in the render output pipeline 870 dispatches pixel shaders to convert the geometric objects into per pixel representations. In some embodiments, pixel shader logic is included in thread execution logic 850. In some embodiments, an application can bypass the rasterizer and depth test component 873 and access un-rasterized vertex data via a stream out unit 823.

The graphics processor 800 has an interconnect bus, interconnect fabric, or some other interconnect mechanism that allows data and message passing amongst the major components of the processor. In some embodiments, execution units 852A-852B and associated logic units (e.g., L1 cache 851, sampler 854, texture cache 858, etc.) interconnect via a data port 856 to perform memory access and communicate with render output pipeline components of the processor. In some embodiments, sampler 854, caches 851, 858 and execution units 852A-852B each have separate memory access paths. In one embodiment the texture cache 858 can also be configured as a sampler cache.

In some embodiments, render output pipeline 870 contains a rasterizer and depth test component 873 that converts vertex-based objects into an associated pixel-based representation. In some embodiments, the rasterizer logic includes a windower/masker unit to perform fixed function triangle and line rasterization. An associated render cache 878 and depth cache 879 are also available in some embodiments. A pixel operations component 877 performs pixel-based operations on the data, though in some instances, pixel operations associated with 2D operations (e.g. bit block image transfers with blending) are performed by the 2D engine 841, or substituted at display time by the display controller 843 using overlay display planes. In some embodiments, a shared L3 cache 875 is available to all graphics components, allowing the sharing of data without the use of main system memory.

In some embodiments, graphics processor media pipeline 830 includes a media engine 837 and a video front-end 834. In some embodiments, video front-end 834 receives pipeline commands from the command streamer 803. In some embodiments, media pipeline 830 includes a separate command streamer. In some embodiments, video front-end 834 processes media commands before sending the command to the media engine 837. In some embodiments, media engine 837 includes thread spawning functionality to spawn threads for dispatch to thread execution logic 850 via thread dispatcher 831.

In some embodiments, graphics processor 800 includes a display engine 840. In some embodiments, display engine 840 is external to processor 800 and couples with the graphics processor via the ring interconnect 802, or some other interconnect bus or fabric. In some embodiments, display engine 840 includes a 2D engine 841 and a display controller 843. In some embodiments, display engine 840 contains special purpose logic capable of operating independently of the 3D pipeline. In some embodiments, display controller 843 couples with a display device (not shown), which may be a system integrated display device, as in a laptop computer, or an external display device attached via a display device connector.

In some embodiments, the geometry pipeline 820 and media pipeline 830 are configurable to perform operations based on multiple graphics and media programming interfaces and are not specific to any one application programming interface (API). In some embodiments, driver software for the graphics processor translates API calls that are specific to a particular graphics or media library into commands that can be processed by the graphics processor. In some embodiments, support is provided for the Open Graphics Library (OpenGL), Open Computing Language (OpenCL), and/or Vulkan graphics and compute API, all from the Khronos Group. In some embodiments, support may also be provided for the Direct3D library from the Microsoft Corporation. In some embodiments, a combination of these libraries may be supported. Support may also be provided for the Open Source Computer Vision Library (OpenCV). A future API with a compatible 3D pipeline would also be supported if a mapping can be made from the pipeline of the future API to the pipeline of the graphics processor.

Graphics Pipeline Programming

FIG. 18A is a block diagram illustrating a graphics processor command format 900 according to some embodiments. FIG. 18B is a block diagram illustrating a graphics processor command sequence 910 according to an embodiment. The solid lined boxes in FIG. 18A illustrate the components that are generally included in a graphics command while the dashed lines include components that are optional or that are only included in a sub-set of the graphics commands. The exemplary graphics processor command format 900 of FIG. 18A includes data fields to identify a client 902, a command operation code (opcode) 904, and data 906 for the command. A sub-opcode 905 and a command size 908 are also included in some commands.

In some embodiments, client 902 specifies the client unit of the graphics device that processes the command data. In some embodiments, a graphics processor command parser examines the client field of each command to condition the further processing of the command and route the command data to the appropriate client unit. In some embodiments, the graphics processor client units include a memory interface unit, a render unit, a 2D unit, a 3D unit, and a media unit. Each client unit has a corresponding processing pipeline that processes the commands. Once the command is received by the client unit, the client unit reads the opcode 904 and, if present, sub-opcode 905 to determine the operation to perform. The client unit performs the command using information in data field 906. For some commands an explicit command size 908 is expected to specify the size of the command. In some embodiments, the command parser automatically determines the size of at least some of the commands based on the command opcode. In some embodiments commands are aligned via multiples of a double word.

The flow diagram in FIG. 18B illustrates an exemplary graphics processor command sequence 910. In some embodiments, software or firmware of a data processing system that features an embodiment of a graphics processor uses a version of the command sequence shown to set up, execute, and terminate a set of graphics operations. A sample command sequence is shown and described for purposes of example only as embodiments are not limited to these specific commands or to this command sequence. Moreover, the commands may be issued as batch of commands in a command sequence, such that the graphics processor will process the sequence of commands in at least partially concurrence.

In some embodiments, the graphics processor command sequence 910 may begin with a pipeline flush command 912 to cause any active graphics pipeline to complete the currently pending commands for the pipeline. In some embodiments, the 3D pipeline 922 and the media pipeline 924 do not operate concurrently. The pipeline flush is performed to cause the active graphics pipeline to complete any pending commands. In response to a pipeline flush, the command parser for the graphics processor will pause command processing until the active drawing engines complete pending operations and the relevant read caches are invalidated. Optionally, any data in the render cache that is marked ‘dirty’ can be flushed to memory. In some embodiments, pipeline flush command 912 can be used for pipeline synchronization or before placing the graphics processor into a low power state.

In some embodiments, a pipeline select command 913 is used when a command sequence requires the graphics processor to explicitly switch between pipelines. In some embodiments, a pipeline select command 913 is required only once within an execution context before issuing pipeline commands unless the context is to issue commands for both pipelines. In some embodiments, a pipeline flush command 912 is required immediately before a pipeline switch via the pipeline select command 913.

In some embodiments, a pipeline control command 914 configures a graphics pipeline for operation and is used to program the 3D pipeline 922 and the media pipeline 924. In some embodiments, pipeline control command 914 configures the pipeline state for the active pipeline. In one embodiment, the pipeline control command 914 is used for pipeline synchronization and to clear data from one or more cache memories within the active pipeline before processing a batch of commands.

In some embodiments, return buffer state commands 916 are used to configure a set of return buffers for the respective pipelines to write data. Some pipeline operations require the allocation, selection, or configuration of one or more return buffers into which the operations write intermediate data during processing. In some embodiments, the graphics processor also uses one or more return buffers to store output data and to perform cross thread communication. In some embodiments, the return buffer state 916 includes selecting the size and number of return buffers to use for a set of pipeline operations.

The remaining commands in the command sequence differ based on the active pipeline for operations. Based on a pipeline determination 920, the command sequence is tailored to the 3D pipeline 922 beginning with the 3D pipeline state 930 or the media pipeline 924 beginning at the media pipeline state 940.

The commands to configure the 3D pipeline state 930 include 3D state setting commands for vertex buffer state, vertex element state, constant color state, depth buffer state, and other state variables that are to be configured before 3D primitive commands are processed. The values of these commands are determined at least in part based on the particular 3D API in use. In some embodiments, 3D pipeline state 930 commands are also able to selectively disable or bypass certain pipeline elements if those elements will not be used.

In some embodiments, 3D primitive 932 command is used to submit 3D primitives to be processed by the 3D pipeline. Commands and associated parameters that are passed to the graphics processor via the 3D primitive 932 command are forwarded to the vertex fetch function in the graphics pipeline. The vertex fetch function uses the 3D primitive 932 command data to generate vertex data structures. The vertex data structures are stored in one or more return buffers. In some embodiments, 3D primitive 932 command is used to perform vertex operations on 3D primitives via vertex shaders. To process vertex shaders, 3D pipeline 922 dispatches shader execution threads to graphics processor execution units.

In some embodiments, 3D pipeline 922 is triggered via an execute 934 command or event. In some embodiments, a register write triggers command execution. In some embodiments execution is triggered via a ‘go’ or ‘kick’ command in the command sequence. In one embodiment, command execution is triggered using a pipeline synchronization command to flush the command sequence through the graphics pipeline. The 3D pipeline will perform geometry processing for the 3D primitives. Once operations are complete, the resulting geometric objects are rasterized and the pixel engine colors the resulting pixels. Additional commands to control pixel shading and pixel back end operations may also be included for those operations.

In some embodiments, the graphics processor command sequence 910 follows the media pipeline 924 path when performing media operations. In general, the specific use and manner of programming for the media pipeline 924 depends on the media or compute operations to be performed. Specific media decode operations may be offloaded to the media pipeline during media decode. In some embodiments, the media pipeline can also be bypassed and media decode can be performed in whole or in part using resources provided by one or more general-purpose processing cores. In one embodiment, the media pipeline also includes elements for general-purpose graphics processor unit (GPGPU) operations, where the graphics processor is used to perform SIMD vector operations using computational shader programs that are not explicitly related to the rendering of graphics primitives.

In some embodiments, media pipeline 924 is configured in a similar manner as the 3D pipeline 922. A set of commands to configure the media pipeline state 940 are dispatched or placed into a command queue before the media object commands 942. In some embodiments, commands for the media pipeline state 940 include data to configure the media pipeline elements that will be used to process the media objects. This includes data to configure the video decode and video encode logic within the media pipeline, such as encode or decode format. In some embodiments, commands for the media pipeline state 940 also support the use of one or more pointers to “indirect” state elements that contain a batch of state settings.

In some embodiments, media object commands 942 supply pointers to media objects for processing by the media pipeline. The media objects include memory buffers containing video data to be processed. In some embodiments, all media pipeline states must be valid before issuing a media object command 942. Once the pipeline state is configured and media object commands 942 are queued, the media pipeline 924 is triggered via an execute command 944 or an equivalent execute event (e.g., register write). Output from media pipeline 924 may then be post processed by operations provided by the 3D pipeline 922 or the media pipeline 924. In some embodiments, GPGPU operations are configured and executed in a similar manner as media operations.

Graphics Software Architecture

FIG. 19 illustrates exemplary graphics software architecture for a data processing system 1000 according to some embodiments. In some embodiments, software architecture includes a 3D graphics application 1010, an operating system 1020, and at least one processor 1030. In some embodiments, processor 1030 includes a graphics processor 1032 and one or more general-purpose processor core(s) 1034. The graphics application 1010 and operating system 1020 each execute in the system memory 1050 of the data processing system. Advantageously, some embodiments of the system 1000 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the system 1000 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

In some embodiments, 3D graphics application 1010 contains one or more shader programs including shader instructions 1012. The shader language instructions may be in a high-level shader language, such as the High Level Shader Language (HLSL) or the OpenGL Shader Language (GLSL). The application also includes executable instructions 1014 in a machine language suitable for execution by the general-purpose processor core 1034. The application also includes graphics objects 1016 defined by vertex data.

In some embodiments, operating system 1020 is a Microsoft® Windows® operating system from the Microsoft Corporation, a proprietary UNIX-like operating system, or an open source UNIX-like operating system using a variant of the Linux kernel. The operating system 1020 can support a graphics API 1022 such as the Direct3D API, the OpenGL API, or the Vulkan API. When the Direct3D API is in use, the operating system 1020 uses a front-end shader compiler 1024 to compile any shader instructions 1012 in HLSL into a lower-level shader language. The compilation may be a just-in-time (JIT) compilation or the application can perform shader pre-compilation. In some embodiments, high-level shaders are compiled into low-level shaders during the compilation of the 3D graphics application 1010. In some embodiments, the shader instructions 1012 are provided in an intermediate form, such as a version of the Standard Portable Intermediate Representation (SPIR) used by the Vulkan API.

In some embodiments, user mode graphics driver 1026 contains a back-end shader compiler 1027 to convert the shader instructions 1012 into a hardware specific representation. When the OpenGL API is in use, shader instructions 1012 in the GLSL high-level language are passed to a user mode graphics driver 1026 for compilation. In some embodiments, user mode graphics driver 1026 uses operating system kernel mode functions 1028 to communicate with a kernel mode graphics driver 1029. In some embodiments, kernel mode graphics driver 1029 communicates with graphics processor 1032 to dispatch commands and instructions.

IP Core Implementations

One or more aspects of at least one embodiment may be implemented by representative code stored on a machine-readable medium which represents and/or defines logic within an integrated circuit such as a processor. For example, the machine-readable medium may include instructions which represent various logic within the processor. When read by a machine, the instructions may cause the machine to fabricate the logic to perform the techniques described herein. Such representations, known as “IP cores,” are reusable units of logic for an integrated circuit that may be stored on a tangible, machine-readable medium as a hardware model that describes the structure of the integrated circuit. The hardware model may be supplied to various customers or manufacturing facilities, which load the hardware model on fabrication machines that manufacture the integrated circuit. The integrated circuit may be fabricated such that the circuit performs operations described in association with any of the embodiments described herein.

FIG. 20A is a block diagram illustrating an IP core development system 1100 that may be used to manufacture an integrated circuit to perform operations according to an embodiment. The IP core development system 1100 may be used to generate modular, re-usable designs that can be incorporated into a larger design or used to construct an entire integrated circuit (e.g., an SOC integrated circuit). A design facility 1130 can generate a software simulation 1110 of an IP core design in a high-level programming language (e.g., C/C++). The software simulation 1110 can be used to design, test, and verify the behavior of the IP core using a simulation model 1112. The simulation model 1112 may include functional, behavioral, and/or timing simulations. A register transfer level (RTL) design 1115 can then be created or synthesized from the simulation model 1112. The RTL design 1115 is an abstraction of the behavior of the integrated circuit that models the flow of digital signals between hardware registers, including the associated logic performed using the modeled digital signals. In addition to an RTL design 1115, lower-level designs at the logic level or transistor level may also be created, designed, or synthesized. Thus, the particular details of the initial design and simulation may vary.

The RTL design 1115 or equivalent may be further synthesized by the design facility into a hardware model 1120, which may be in a hardware description language (HDL), or some other representation of physical design data. The HDL may be further simulated or tested to verify the IP core design. The IP core design can be stored for delivery to a 3rd party fabrication facility 1165 using non-volatile memory 1140 (e.g., hard disk, flash memory, or any non-volatile storage medium). Alternatively, the IP core design may be transmitted (e.g., via the Internet) over a wired connection 1150 or wireless connection 1160. The fabrication facility 1165 may then fabricate an integrated circuit that is based at least in part on the IP core design. The fabricated integrated circuit can be configured to perform operations in accordance with at least one embodiment described herein.

FIG. 20B illustrates a cross-section side view of an integrated circuit package assembly 1170, according to some embodiments described herein. The integrated circuit package assembly 1170 illustrates an implementation of one or more processor or accelerator devices as described herein. The package assembly 1170 includes multiple units of hardware logic 1172, 1174 connected to a substrate 1180. The logic 1172, 1174 may be implemented at least partly in configurable logic or fixed-functionality logic hardware, and can include one or more portions of any of the processor core(s), graphics processor(s), or other accelerator devices described herein. Each unit of logic 1172, 1174 can be implemented within a semiconductor die and coupled with the substrate 1180 via an interconnect structure 1173. The interconnect structure 1173 may be configured to route electrical signals between the logic 1172, 1174 and the substrate 1180, and can include interconnects such as, but not limited to bumps or pillars. In some embodiments, the interconnect structure 1173 may be configured to route electrical signals such as, for example, input/output (I/O) signals and/or power or ground signals associated with the operation of the logic 1172, 1174. In some embodiments, the substrate 1180 is an epoxy-based laminate substrate. The package substrate 1180 may include other suitable types of substrates in other embodiments. The package assembly 1170 can be connected to other electrical devices via a package interconnect 1183. The package interconnect 1183 may be coupled to a surface of the substrate 1180 to route electrical signals to other electrical devices, such as a motherboard, other chipset, or multi-chip module.

In some embodiments, the units of logic 1172, 1174 are electrically coupled with a bridge 1182 that is configured to route electrical signals between the logic 1172, 1174. The bridge 1182 may be a dense interconnect structure that provides a route for electrical signals. The bridge 1182 may include a bridge substrate composed of glass or a suitable semiconductor material. Electrical routing features can be formed on the bridge substrate to provide a chip-to-chip connection between the logic 1172, 1174.

Although two units of logic 1172, 1174 and a bridge 1182 are illustrated, embodiments described herein may include more or fewer logic units on one or more dies. The one or more dies may be connected by zero or more bridges, as the bridge 1182 may be excluded when the logic is included on a single die. Alternatively, multiple dies or units of logic can be connected by one or more bridges. Additionally, multiple logic units, dies, and bridges can be connected together in other possible configurations, including three-dimensional configurations.

Exemplary System on a Chip Integrated Circuit

FIGS. 21-23 illustrated exemplary integrated circuits and associated graphics processors that may be fabricated using one or more IP cores, according to various embodiments described herein. In addition to what is illustrated, other logic and circuits may be included, including additional graphics processors/cores, peripheral interface controllers, or general-purpose processor cores.

FIG. 21 is a block diagram illustrating an exemplary system on a chip integrated circuit 1200 that may be fabricated using one or more IP cores, according to an embodiment. Exemplary integrated circuit 1200 includes one or more application processor(s) 1205 (e.g., CPUs), at least one graphics processor 1210, and may additionally include an image processor 1215 and/or a video processor 1220, any of which may be a modular IP core from the same or multiple different design facilities. Integrated circuit 1200 includes peripheral or bus logic including a USB controller 1225, UART controller 1230, an SPI/SDIO controller 1235, and an I2S/I2C controller 1240. Additionally, the integrated circuit can include a display device 1245 coupled to one or more of a high-definition multimedia interface (HDMI) controller 1250 and a mobile industry processor interface (MIPI) display interface 1255. Storage may be provided by a flash memory subsystem 1260 including flash memory and a flash memory controller. Memory interface may be provided via a memory controller 1265 for access to SDRAM or SRAM memory devices. Some integrated circuits additionally include an embedded security engine 1270. Advantageously, some embodiments of the circuit 1200 may perform primitive replication at a vertex shader. For example, new API constructs may enable primitive replication at the vertex shader, improving CPU-level overhead and avoiding problems incurred by GS replication. In particular, in some embodiments the graphics driver may include primitive replication commands and the vertex shader may include logic related to position calculation (e.g., moved from the GS to the VS). For example, the circuit 1200 may implement one or more aspects of the method 25 (FIGS. 3A to 3C).

FIGS. 22A-22B are block diagrams illustrating exemplary graphics processors for use within an SoC, according to embodiments described herein. FIG. 22A illustrates an exemplary graphics processor 1310 of a system on a chip integrated circuit that may be fabricated using one or more IP cores, according to an embodiment. FIG. 22B illustrates an additional exemplary graphics processor 1340 of a system on a chip integrated circuit that may be fabricated using one or more IP cores, according to an embodiment. Graphics processor 1310 of FIG. 22A is an example of a low power graphics processor core. Graphics processor 1340 of FIG. 22B is an example of a higher performance graphics processor core. Each of the graphics processors 1310, 1340 can be variants of the graphics processor 1210 of FIG. 21.

As shown in FIG. 22A, graphics processor 1310 includes a vertex processor 1305 and one or more fragment processor(s) 1315A-1315N (e.g., 1315A, 1315B, 1315C, 1315D, through 1315N-1, and 1315N). Graphics processor 1310 can execute different shader programs via separate logic, such that the vertex processor 1305 is optimized to execute operations for vertex shader programs, while the one or more fragment processor(s) 1315A-1315N execute fragment (e.g., pixel) shading operations for fragment or pixel shader programs. The vertex processor 1305 performs the vertex processing stage of the 3D graphics pipeline and generates primitives and vertex data. The fragment processor(s) 1315A-1315N use the primitive and vertex data generated by the vertex processor 1305 to produce a framebuffer that is displayed on a display device. In one embodiment, the fragment processor(s) 1315A-1315N are optimized to execute fragment shader programs as provided for in the OpenGL API, which may be used to perform similar operations as a pixel shader program as provided for in the Direct 3D API.

Graphics processor 1310 additionally includes one or more memory management units (MMUs) 1320A-1320B, cache(s) 1325A-1325B, and circuit interconnect(s) 1330A-1330B. The one or more MMU(s) 1320A-1320B provide for virtual to physical address mapping for the graphics processor 1310, including for the vertex processor 1305 and/or fragment processor(s) 1315A-1315N, which may reference vertex or image/texture data stored in memory, in addition to vertex or image/texture data stored in the one or more cache(s) 1325A-1325B. In one embodiment the one or more MMU(s) 1320A-1320B may be synchronized with other MMUs within the system, including one or more MMUs associated with the one or more application processor(s) 1205, image processor 1215, and/or video processor 1220 of FIG. 21, such that each processor 1205-1220 can participate in a shared or unified virtual memory system. The one or more circuit interconnect(s) 1330A-1330B enable graphics processor 1310 to interface with other IP cores within the SoC, either via an internal bus of the SoC or via a direct connection, according to embodiments.

As shown FIG. 22B, graphics processor 1340 includes the one or more MMU(s) 1320A-1320B, caches 1325A-1325B, and circuit interconnects 1330A-1330B of the graphics processor 1310 of FIG. 22A. Graphics processor 1340 includes one or more shader core(s) 1355A-1355N (e.g., 1455A, 1355B, 1355C, 1355D, 1355E, 1355F, through 1355N-1, and 1355N), which provides for a unified shader core architecture in which a single core or type or core can execute all types of programmable shader code, including shader program code to implement vertex shaders, fragment shaders, and/or compute shaders. The exact number of shader cores present can vary among embodiments and implementations. Additionally, graphics processor 1340 includes an inter-core task manager 1345, which acts as a thread dispatcher to dispatch execution threads to one or more shader cores 1355A-1355N and a tiling unit 1358 to accelerate tiling operations for tile-based rendering, in which rendering operations for a scene are subdivided in image space, for example to exploit local spatial coherence within a scene or to optimize use of internal caches.

FIGS. 23A-23B illustrate additional exemplary graphics processor logic according to embodiments described herein. FIG. 23A illustrates a graphics core 1400 that may be included within the graphics processor 1210 of FIG. 21, and may be a unified shader core 1355A-1355N as in FIG. 22B. FIG. 23B illustrates an additional general-purpose graphics processing unit 1430, which is a highly-parallel general-purpose graphics processing unit suitable for deployment on a multi-chip module.

As shown in FIG. 23A, the graphics core 1400 includes a shared instruction cache 1402, a texture unit 1418, and a cache/shared memory 1420 that are common to the execution resources within the graphics core 1400. The graphics core 1400 can include multiple slices 1401A-1401N or partition for each core, and a graphics processor can include multiple instances of the graphics core 1400. The slices 1401A-1401N can include support logic including a local instruction cache 1404A-1404N, a thread scheduler 1406A-1406N, a thread dispatcher 1408A-1408N, and a set of registers 1410A-1440N. To perform logic operations, the slices 1401A-1401N can include a set of additional function units (AFUs 1412A-1412N), floating-point units (FPU 1414A-1414N), integer arithmetic logic units (ALUs 1416-1416N), address computational units (ACU 1413A-1413N), double-precision floating-point units (DPFPU 1415A-1415N), and matrix processing units (MPU 1417A-1417N).

Some of the computational units operate at a specific precision. For example, the FPUs 1414A-1414N can perform single-precision (32-bit) and half-precision (16-bit) floating point operations, while the DPFPUs 1415A-1415N perform double precision (64-bit) floating point operations. The ALUs 1416A-1416N can perform variable precision integer operations at 8-bit, 16-bit, and 32-bit precision, and can be configured for mixed precision operations. The MPUs 1417A-1417N can also be configured for mixed precision matrix operations, including half-precision floating point and 8-bit integer operations. The MPUs 1417-1417N can perform a variety of matrix operations to accelerate machine learning application frameworks, including enabling support for accelerated general matrix to matrix multiplication (GEMM). The AFUs 1412A-1412N can perform additional logic operations not supported by the floating-point or integer units, including trigonometric operations (e.g., Sine, Cosine, etc.).

As shown in FIG. 23B, a general-purpose processing unit (GPGPU) 1430 can be configured to enable highly-parallel compute operations to be performed by an array of graphics processing units. Additionally, the GPGPU 1430 can be linked directly to other instances of the GPGPU to create a multi-GPU cluster to improve training speed for particularly deep neural networks. The GPGPU 1430 includes a host interface 1432 to enable a connection with a host processor. In one embodiment the host interface 1432 is a PCI Express interface. However, the host interface can also be a vendor specific communications interface or communications fabric. The GPGPU 1430 receives commands from the host processor and uses a global scheduler 1434 to distribute execution threads associated with those commands to a set of compute clusters 1436A-1436H. The compute clusters 1436A-1436H share a cache memory 1438. The cache memory 1438 can serve as a higher-level cache for cache memories within the compute clusters 1436A-1436H.

The GPGPU 1430 includes memory 1444A-1444B coupled with the compute clusters 1436A-1436H via a set of memory controllers 1442A-1442B. In various embodiments, the memory 1434A-1434B can include various types of memory devices including dynamic random access memory (DRAM) or graphics random access memory, such as synchronous graphics random access memory (SGRAM), including graphics double data rate (GDDR) memory.

In one embodiment the compute clusters 1436A-1436H each include a set of graphics cores, such as the graphics core 1400 of FIG. 23A, which can include multiple types of integer and floating point logic units that can perform computational operations at a range of precisions including suited for machine learning computations. For example and in one embodiment at least a subset of the floating point units in each of the compute clusters 1436A-1436H can be configured to perform 16-bit or 32-bit floating point operations, while a different subset of the floating point units can be configured to perform 64-bit floating point operations.

Multiple instances of the GPGPU 1430 can be configured to operate as a compute cluster. The communication mechanism used by the compute cluster for synchronization and data exchange varies across embodiments. In one embodiment the multiple instances of the GPGPU 1430 communicate over the host interface 1432. In one embodiment the GPGPU 1430 includes an I/O hub 1439 that couples the GPGPU 1430 with a GPU link 1440 that enables a direct connection to other instances of the GPGPU. In one embodiment the GPU link 1440 is coupled to a dedicated GPU-to-GPU bridge that enables communication and synchronization between multiple instances of the GPGPU 1430. In one embodiment the GPU link 1440 couples with a high speed interconnect to transmit and receive data to other GPGPUs or parallel processors. In one embodiment the multiple instances of the GPGPU 1430 are located in separate data processing systems and communicate via a network device that is accessible via the host interface 1432. In one embodiment the GPU link 1440 can be configured to enable a connection to a host processor in addition to or as an alternative to the host interface 1432.

While the illustrated configuration of the GPGPU 1430 can be configured to train neural networks, one embodiment provides alternate configuration of the GPGPU 1430 that can be configured for deployment within a high performance or low power inferencing platform. In an inferencing configuration the GPGPU 1430 includes fewer of the compute clusters 1436A-1436H relative to the training configuration. Additionally, the memory technology associated with the memory 1434A-1434B may differ between inferencing and training configurations, with higher bandwidth memory technologies devoted to training configurations. In one embodiment the inferencing configuration of the GPGPU 1430 can support inferencing specific instructions. For example, an inferencing configuration can provide support for one or more 8-bit integer dot product instructions, which are commonly used during inferencing operations for deployed neural networks.

Advantageously, any of the above systems, processors, graphics processors, apparatuses, and/or methods may be integrated or configured with any of the various embodiments described herein (e.g., or portions thereof), including, for example, those described in the below Additional Notes and Examples.

Additional Notes and Examples

Example 1 may include a graphics processor system, comprising a processor, memory communicatively coupled to the processor, and logic communicatively coupled to the processor and memory to determine one or more conditions for a set of primitives, and perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives.

Example 2 may include the system of Example 1, wherein the logic is further to reconfigure a graphics pipeline to perform primitive replication at the vertex shader.

Example 3 may include the system of Example 2, wherein the logic is further to configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.

Example 4 may include the system of Example 3, wherein each of the first and second targets respectively include one or more of a render target and a viewport.

Example 5 may include the system of Example 1, wherein the logic is further to determine a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, determine a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and determine a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport.

Example 6 may include the system of Example 5, wherein the logic is further to determine if each of the first, second, and third conditions are met, and if met, to move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and move operations related to all other output attributes from the geometry shader to the vertex shader.

Example 7 may include a semiconductor package apparatus, comprising one or more substrates, and logic coupled to the one or more substrates, wherein the logic is at least partly implemented in one or more of configurable logic and fixed-functionality hardware logic, the logic coupled to the one or more substrates to determine one or more conditions for a set of primitives, and perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives.

Example 8 may include the apparatus of Example 7, wherein the logic is further to reconfigure a graphics pipeline to perform primitive replication at the vertex shader.

Example 9 may include the apparatus of Example 8, wherein the logic is further to configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.

Example 10 may include the apparatus of Example 9, wherein each of the first and second targets respectively include one or more of a render target and a viewport.

Example 11 may include the apparatus of Example 7, wherein the logic is further to determine a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, determine a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and determine a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport.

Example 12 may include the apparatus of Example 11, wherein the logic is further to determine if each of the first, second, and third conditions are met, and if met, to move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and move operations related to all other output attributes from the geometry shader to the vertex shader.

Example 13 may include the apparatus of any of Examples 7 to 12, wherein the logic coupled to the one or more substrates includes transistor channel regions that are positioned within the one or more substrates.

Example 14 may include a method of processing graphics, comprising determining one or more conditions for a set of primitives, and performing primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives.

Example 15 may include the method of Example 14, further comprising reconfiguring a graphics pipeline to perform primitive replication at the vertex shader.

Example 16 may include the method of Example 15, further comprising configuring the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.

Example 17 may include the method of Example 16, wherein each of the first and second targets respectively include one or more of a render target and a viewport.

Example 18 may include the method of Example 14, further comprising determining a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, determining a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and determining a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport.

Example 19 may include the method of Example 18, further comprising determining if each of the first, second, and third conditions are met, and if met moving operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and moving operations related to all other output attributes from the geometry shader to the vertex shader.

Example 20 may include at least one computer readable storage medium, comprising a set of instructions, which when executed by a computing device, cause the computing device to determine one or more conditions for a set of primitives, and perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives.

Example 21 may include the at least one computer readable storage medium of Example 20, comprising a further set of instructions, which when executed by the computing device, cause the computing device to reconfigure a graphics pipeline to perform primitive replication at the vertex shader.

Example 22 may include the at least one computer readable storage medium of Example 21, comprising a further set of instructions, which when executed by the computing device, cause the computing device to configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.

Example 23 may include the at least one computer readable storage medium of Example 22, wherein each of the first and second targets respectively include one or more of a render target and a viewport.

Example 24 may include the at least one computer readable storage medium of Example 20, comprising a further set of instructions, which when executed by the computing device, cause the computing device to determine a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, determine a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and determine a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport.

Example 25 may include the at least one computer readable storage medium of Example 24, comprising a further set of instructions, which when executed by the computing device, cause the computing device to determine if each of the first, second, and third conditions are met, and if met, to move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and move operations related to all other output attributes from the geometry shader to the vertex shader.

Example 26 may include a graphics processor apparatus, comprising means for determining one or more conditions for a set of primitives, and means for performing primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives.

Example 27 may include the apparatus of Example 26, further comprising means for reconfiguring a graphics pipeline to perform primitive replication at the vertex shader.

Example 28 may include the apparatus of Example 27, further comprising means for configuring the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.

Example 29 may include the apparatus of Example 28, wherein each of the first and second targets respectively include one or more of a render target and a viewport.

Example 30 may include the apparatus of Example 26, further comprising means for determining a first condition based on if only one or more of a layer and a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader, means for determining a second condition based on if a number of declared emitted vertices in the geometry shader is less than a threshold, and means for determining a third condition based on if each vertex from the geometry is emitted into one of a separate render target and a separate viewport.

Example 31 may include the apparatus of Example 30, further comprising means for determining if each of the first, second, and third conditions are met, and if met means for moving operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader, and means for moving operations related to all other output attributes from the geometry shader to the vertex shader.

Embodiments are applicable for use with all types of semiconductor integrated circuit (“IC”) chips. Examples of these IC chips include but are not limited to processors, controllers, chipset components, programmable logic arrays (PLAs), memory chips, network chips, systems on chip (SoCs), SSD/NAND controller ASICs, and the like. In addition, in some of the drawings, signal conductor lines are represented with lines. Some may be different, to indicate more constituent signal paths, have a number label, to indicate a number of constituent signal paths, and/or have arrows at one or more ends, to indicate primary information flow direction. This, however, should not be construed in a limiting manner. Rather, such added detail may be used in connection with one or more exemplary embodiments to facilitate easier understanding of a circuit. Any represented signal lines, whether or not having additional information, may actually comprise one or more signals that may travel in multiple directions and may be implemented with any suitable type of signal scheme, e.g., digital or analog lines implemented with differential pairs, optical fiber lines, and/or single-ended lines.

Example sizes/models/values/ranges may have been given, although embodiments are not limited to the same. As manufacturing techniques (e.g., photolithography) mature over time, it is expected that devices of smaller size could be manufactured. In addition, well known power/ground connections to IC chips and other components may or may not be shown within the figures, for simplicity of illustration and discussion, and so as not to obscure certain aspects of the embodiments. Further, arrangements may be shown in block diagram form in order to avoid obscuring embodiments, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the embodiment is to be implemented, i.e., such specifics should be well within purview of one skilled in the art. Where specific details (e.g., circuits) are set forth in order to describe example embodiments, it should be apparent to one skilled in the art that embodiments can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting.

The term “coupled” may be used herein to refer to any type of relationship, direct or indirect, between the components in question, and may apply to electrical, mechanical, fluid, optical, electromagnetic, electromechanical or other connections. In addition, the terms “first”, “second”, etc. may be used herein only to facilitate discussion, and carry no particular temporal or chronological significance unless otherwise indicated.

As used in this application and in the claims, a list of items joined by the term “one or more of” may mean any combination of the listed terms. For example, the phrase “one or more of A, B, and C” and the phrase “one or more of A, B, or C” both may mean A; B; C; A and B; A and C; B and C; or A, B and C.

Those skilled in the art will appreciate from the foregoing description that the broad techniques of the embodiments can be implemented in a variety of forms. Therefore, while the embodiments have been described in connection with particular examples thereof, the true scope of the embodiments should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims. 

1. A graphics processor system, comprising: a processor; memory communicatively coupled to the processor; and logic communicatively coupled to the processor and memory to: determine one or more conditions for a set of primitives; perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives; determine a first condition based on whether only one or more of a layer or a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader; determine a second condition based on whether a number of declared emitted vertices in the geometry shader is less than a threshold; determine a third condition based on whether each vertex from the geometry is emitted into one of a separate render target and a separate viewport; and determine whether each of the first, second, and third conditions are met, and if met, to: move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader; and move operations related to all other output attributes from the geometry shader to the vertex shader.
 2. The system of claim 1, wherein the logic is further to: reconfigure a graphics pipeline to perform primitive replication at the vertex shader.
 3. The system of claim 2, wherein the logic is further to: configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.
 4. The system of claim 3, wherein each of the first and second targets respectively include one or more of a render target and a viewport.
 5. (canceled)
 6. (canceled)
 7. A semiconductor package apparatus, comprising: one or more substrates; and logic coupled to the one or more substrates, wherein the logic is at least partly implemented in one or more of configurable logic and fixed-functionality hardware logic, the logic coupled to the one or more substrates to: determine one or more conditions for a set of primitives; perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives; determine a first condition based on whether only one or more of a layer or a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader; determine a second condition based on whether a number of declared emitted vertices in the geometry shader is less than a threshold; determine a third condition based on whether each vertex from the geometry is emitted into one of a separate render target and a separate viewport; and determine whether each of the first, second, and third conditions are met, and if met, to: move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader; and move operations related to all other output attributes from the geometry shader to the vertex shader.
 8. The apparatus of claim 7, wherein the logic is further to: reconfigure a graphics pipeline to perform primitive replication at the vertex shader.
 9. The apparatus of claim 8, wherein the logic is further to: configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.
 10. The apparatus of claim 9, wherein each of the first and second targets respectively include one or more of a render target and a viewport.
 11. (canceled)
 12. (canceled)
 13. The apparatus of claim 7, wherein the logic coupled to the one or more substrates includes transistor channel regions that are positioned within the one or more substrates.
 14. A method of processing graphics, comprising: determining one or more conditions for a set of primitives; and performing primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives; determining a first condition based on whether only one or more of a layer or a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader; determining a second condition based on whether a number of declared emitted vertices in the geometry shader is less than a threshold; determining a third condition based on whether each vertex from the geometry is emitted into one of a separate render target and a separate viewport; and determining whether each of the first, second, and third conditions are met, and if met: moving operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader; and moving operations related to all other output attributes from the geometry shader to the vertex shader.
 15. The method of claim 14, further comprising: reconfiguring a graphics pipeline to perform primitive replication at the vertex shader.
 16. The method of claim 15, further comprising: configuring the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.
 17. The method of claim 16, wherein each of the first and second targets respectively include one or more of a render target and a viewport.
 18. (canceled)
 19. (canceled)
 20. At least one non-transitory computer readable storage medium, comprising a set of instructions, which when executed by a computing device, cause the computing device to: determine one or more conditions for a set of primitives; perform primitive replication at a vertex shader based on the determined one or more conditions for the set of primitives; determine a first condition based on whether only one or more of a layer or a viewport, together with position output attributes, are changed per emitted vertex in a geometry shader; determine a second condition based on whether a number of declared emitted vertices in the geometry shader is less than a threshold; determine a third condition based on whether each vertex from the geometry is emitted into one of a separate render target and a separate viewport; and determine whether each of the first, second, and third conditions are met, and if met, to: move operations related to position, layer, viewport calculations, and primitive replication from the geometry shader to the vertex shader; and move operations related to all other output attributes from the geometry shader to the vertex shader.
 21. The at least one non-transitory computer readable storage medium of claim 20, comprising a further set of instructions, which when executed by the computing device, cause the computing device to: reconfigure a graphics pipeline to perform primitive replication at the vertex shader.
 22. The at least one non-transitory computer readable storage medium of claim 21, comprising a further set of instructions, which when executed by the computing device, cause the computing device to: configure the vertex shader to generate replicated primitives of original primitives and adjust respective position attributes of the replicated primitives for a second target relative to a first target for the original primitives.
 23. The at least one non-transitory computer readable storage medium of claim 22, wherein each of the first and second targets respectively include one or more of a render target and a viewport.
 24. (canceled)
 25. (canceled) 